JP6125828B2 - Motion recognition device - Google Patents

Description

The present invention relates to a motion recognition apparatus having a three-dimensional distance image sensor to which a Time Of Flight (TOF) method is applied.

Note that in this specification, a semiconductor device refers to all devices that can function by utilizing semiconductor characteristics, and an electro-optical device, a semiconductor circuit, and an electronic device are all semiconductor devices.

In recent years, three-dimensional images and displays have progressed, and development of three-dimensional information acquisition technology has been actively conducted. A three-dimensional distance image sensor capable of acquiring spatial three-dimensional information in real time is expected to be applied in various applications such as a gesture recognition system and a computer vision system. Non-Patent Document 1 describes a three-dimensional distance image sensor that applies a TOF method to irradiate light from a light source to an object to be detected to acquire distance image information. The sensor can realize a small and low-cost system as compared with a stereo method, a laser scanning method, or the like.

In addition, motion recognition technology that detects position change information, shape change information, and the like of an object to be detected and digitally records motion information has been widely used in fields such as sports medicine, movies, and computer animation. . In Patent Document 1, an information processing apparatus including a user interface for easily detecting a complicated operation of a user is provided.

Patent Document 2 proposes a system for calculating the three-dimensional distance image information from a plurality of two-dimensional images acquired by imaging with a plurality of cameras and recognizing the operation of the detected object. Patent Document 3 proposes a human body motion recognition sensor that detects infrared rays emitted from the human body and recognizes the motion of the human body.

JP 2011-8601 A JP 2001-273503 A JP-A-7-288875

S. J. et al. Kim et al, "A Three-Dimensional Time-of-Flight CMOS Image Sensor Sensor Pinned-Photodiode Pixel Structure," IEEE Electron Device Letter. 31, no. 11, Nov. 2010.

In Patent Document 1, a user wears a marker composed of a sensor or the like on each part of the body. By measuring the time change of the marker (time change of position, time change of shape, etc.), the complicated operation of the user is strictly recorded. However, there is a problem that it takes a lot of time to attach and detach the marker.

In Patent Document 2, the detection object is always exposed to a large number of cameras. In order to prevent the detected object from entering the blind spot of the camera, the operation must be performed within a relatively narrow range specified in advance, and since a large number of cameras and sensors are required, the entire system is expensive. There is a problem of becoming.

Furthermore, from a plurality of two-dimensional images (color images) of the detected object captured by a large number of cameras, based on the deviation of the image, the principle of triangulation is used to detect 3 of the detected object in the imaging area. Dimensional distance image information is estimated and calculated. Therefore, there is a problem that it is necessary to perform background processing or the like in order to extract the position of the detected object from an image including an object other than the detected object, which takes useless time for the arithmetic processing. Considering accurate alignment of a large number of cameras and mounting of an automatic focusing mechanism for the cameras, there is a big problem in simplifying the camera structure.

In the method proposed in Non-Patent Document 1, different detection signals are acquired by two times of infrared light irradiation, but it is difficult to detect each reflected infrared light continuously. . That is, there is a time difference between the end of the first imaging and the start of the next imaging. For this reason, there exists a problem that it is unsuitable for the position detection of a mobile body. In particular, when the object to be detected moves at a high speed, the decrease in position detection accuracy becomes significant.

Moreover, when using the infrared rays radiated from the human body as in Patent Document 3, noise caused by changes in the body temperature of the human body cannot be ignored.

In view of the above-described problems, an object is to provide a motion recognition device that can recognize the motion of a detected object without contact with the detected object.

Another object is to provide a motion recognition device that has a simple configuration and can recognize the motion of the detected object without selecting the state of the detected object.

Another object is to capture an object to be detected that moves at high speed without distortion, and to easily acquire position change information and shape change information of the object to be detected.

The detection of position change information and shape change information is simplified by using a three-dimensional distance image sensor to which the TOF method is applied in a motion recognition device.

In addition, by using a three-dimensional distance image sensor to which the TOF method is applied for the motion recognition device, it is possible to simplify detection of position change information and shape change information including color image information.

One embodiment of the present invention disclosed in this specification includes an imaging device that acquires distance image information of an object to be detected, generates imaging data from the distance image information, and outputs the imaging data; and a specific object pattern A first storage unit that stores the image, a second storage unit that stores the specific operation pattern, an image storage unit that stores imaging data that changes over time, and imaging data stored in the image storage unit Object data that extracts the imaging data from the operation start time to the operation end time of the detected object, compares the extracted imaging data with the specific object pattern, and selects the best matching object data at each time A detection unit; a third storage unit that stores object data at each time; object data from an operation start time to an operation end time of the detected object stored in the third storage unit; and a specific operation pattern. Compared to, An image processing apparatus having an operation data detecting unit that estimates operation data, a fourth storage unit that stores operation data, an output control unit that generates output data from the operation data, and outputs the output data; An information processing apparatus comprising: an information processing apparatus that recognizes an operation of an object to be detected based on data and executes an operation defined based on output data.

In the above, the imaging device detects the distance image information of the detected object, and detects the time until the light irradiated from the light source reaches the detected object and the light reflected by the detected object arrives at the imaging device. It can be obtained by the relational expression between time and speed of light.

In the above, the imaging apparatus performs distance image information of the detected object from the light source on the detected object, the first irradiation and the second irradiation having different timing from the first irradiation for the same time, and the first The first reflected light of the object to be detected by the irradiation of and the second reflected light of the object to be detected by the second irradiation are detected by the photodiode, and the floating diffusion is used by using the photocurrent output from the photodiode. In order to perform the first imaging with the potential of the gate electrode of the first transistor that changes the amount of charge accumulated in the node, at least the first reflected light from the object to be detected by the first irradiation is a photodiode. The first detection signal S1 is obtained by detecting the first reflected light in the high potential period from the time before the start of irradiation to the time until the time after the end of the first irradiation. Get In order to perform the second imaging, at least before the time when the second irradiation ends, after the time when the second reflected light from the detection object by the second irradiation finishes irradiating the photodiode. The second detection signal S2 is obtained by detecting the second reflected light in the high potential period, and the first irradiation period T, the speed of light c, and the first detection signal S1. Using the second detection signal S2, the distance x from the light source to the object to be detected can be obtained by calculating according to Equation (1).

In the above, the comparison with the specific object pattern may be performed by calculating a correlation coefficient.

In the above, the comparison with the specific operation pattern may be performed by calculating a correlation coefficient.

In the above, the imaging device may include a plurality of photosensors including a photodiode, a first transistor, a second transistor, and a third transistor.

In the above, an oxide semiconductor material may be used for the semiconductor layer of the first transistor.

In the above, a silicon material may be used for the semiconductor layer of the first transistor.

Further, according to one embodiment of the present invention disclosed in this specification, distance image information of an object to be detected is acquired by performing first imaging and second imaging with one irradiation light without a time difference, and An imaging device that generates imaging data from the distance image information and outputs the imaging data; a first storage unit that stores a specific object pattern; a second storage unit that stores a specific operation pattern; Extracting imaging data from the operation start time to the operation end time of the detected object from the image storage unit that stores imaging data that changes over time, and the imaging data stored in the image storage unit, and the extracted imaging An object data detection unit that compares the data with a specific object pattern and selects the most consistent object data at each time; a third storage unit that stores object data at each time; and a third storage unit Of detected objects stored in The object data from the start time to the action end time is compared with the specific action pattern, the action data detecting part for estimating the action data, the fourth storage part for storing the action data, and the output data from the action data. An image processing apparatus having an output control unit that generates and outputs the output data, and an information processing apparatus that recognizes the operation of the detected object based on the output data and executes an operation defined based on the output data And a motion recognition device.

In the above, the imaging device detects the distance image information of the detected object, and detects the time until the light irradiated from the light source reaches the detected object and the light reflected by the detected object arrives at the imaging device. Then, the reflected light can be detected continuously before and after the end of light irradiation, and can be obtained by the relational expression between time and speed of light.

In the above, the imaging apparatus irradiates the detected object with the distance image information from the light source to the detected object, and the first and second photodiodes adjacent to each other detect the same of the detected object. The reflected light from one point is absorbed, and the potential of the gate electrode of the first transistor that changes the amount of charge accumulated in the first node is changed by using the photocurrent output from the first photodiode. The first detection signal S1 is obtained by detecting the reflected light applied to the first photodiode during the high potential period from the start of absorption of light to the moment when the light irradiation ends. Then, using the photocurrent output from the second photodiode, the potential of the gate electrode of the second transistor that changes the amount of charge accumulated in the second node is reflected from the moment when the light irradiation ends. End of light absorption The second detection signal S2 is obtained by detecting the reflected light applied to the second photodiode in the high potential period until the second detection signal S2 is obtained. The distance x from the light source to the detection object can be obtained by calculating according to the equation (1) using the detection signal S2, the light irradiation period T, and the speed of light c.

In the above, the comparison with the specific object pattern may be performed by calculating a correlation coefficient.

In the above, the comparison with the specific operation pattern may be performed by calculating a correlation coefficient.

In the above, the imaging device includes a plurality of photosensors including a photodiode, a first transistor, a second transistor, and a third transistor, and the adjacent first photodiode and second photodiode. Can absorb the reflected light from the same point of the object to be detected.

In the above, a silicon material may be used for the semiconductor layer of the first transistor. By using a semiconductor layer having high mobility for the first transistor that is electrically connected to the floating diffusion node, the gate electrode can increase the amplification degree of the charge accumulated in the floating diffusion node. A more sensitive amplification transistor can be configured.

In the above, a silicon material may be used for the semiconductor layer of the second transistor. By using a silicon material for the semiconductor layer of the second transistor in which one of the source electrode and the drain electrode is electrically connected to one of the source electrode and the drain electrode of the first transistor, the second transistor is turned on. The current can be increased. Therefore, the data reading time can be shortened and the output of the photosensor can be controlled at high speed. Further, by using a semiconductor layer with high mobility, the switching speed of the output control line can be controlled in a wider range.

In the above, an oxide semiconductor material may be used for the semiconductor layer of the third transistor. One of the source electrode and the drain electrode is electrically connected to the floating diffusion node, and the other of the source electrode and the drain electrode is electrically connected to the photodiode. By using the transistor, the off-state current of the transistor can be extremely reduced. Since the floating diffusion node can hold the accumulated electric charge for a long time, the imaging device mounted on the motion recognition device receives light (irradiation light) emitted from the light source at the object to be detected. Furthermore, it is possible to detect the time until the light (reflected light) reflected by the detection object arrives at the imaging apparatus with higher accuracy, and to acquire highly reliable imaging data.

In the above, by using a silicon material as the semiconductor layer of the first transistor and the second transistor and using an oxide semiconductor material as the semiconductor layer of the third transistor, the pixel can be miniaturized. A motion recognition device having an imaging device capable of high performance and high speed operation can be obtained.

In the above, a silicon material may be used for the semiconductor layers of the first transistor, the second transistor, and the third transistor. When the object to be detected moves at a high speed, the photosensor can be operated at a higher speed by using a silicon material as a semiconductor layer of all transistors used in the photosensor.

One embodiment of the present invention disclosed in this specification acquires two-dimensional image information and three-dimensional distance image information of a detection object, generates imaging data from the image information, and outputs the imaging data. An imaging device, a first storage unit that stores a specific object pattern, a second storage unit that stores a specific operation pattern, an image storage unit that stores imaging data that changes over time, and an image storage unit From the stored imaging data, the imaging data from the operation start time to the operation end time of the detected object is extracted, and the extracted imaging data and the specific object pattern are compared, and the best match at each time Object data detection unit for selecting object data, a third storage unit for storing object data at each time, and object data from the operation start time to the operation end time of the detected object stored in the third storage unit And specific behavior A motion data detector that compares the patterns and estimates motion data; a fourth storage that stores motion data; and an output controller that generates output data from the motion data and outputs the output data. What is claimed is: 1. An operation recognition apparatus comprising: an image processing apparatus having: an information processing apparatus that recognizes an operation of an object to be detected based on output data and executes an operation defined based on the output data .

In the above, the imaging apparatus is configured to receive the three-dimensional distance image information of the detected object, the infrared light irradiated from the light source arrives at the detected object, and the infrared light reflected by the detected object arrives at the imaging apparatus. It is possible to detect the time until the image is obtained and obtain it by the relational expression between time and the speed of light.

In the above, the imaging apparatus performs the first infrared light irradiation and the second infrared light irradiation, which are different in timing from the first infrared light irradiation, from the light source on the same time for the first time. The potential of the gate electrode of the first transistor that absorbs visible light and changes the amount of charge accumulated in the first floating diffusion node using the photocurrent output from the first photodiode. The reflected light from the object to be detected by the second infrared light irradiation is at least before the reflected light from the object to be detected by the first infrared light irradiation is irradiated to the first photodiode, A high potential is applied until the first photodiode is irradiated, and two-dimensional image information of the object to be detected is acquired by detecting visible light in the high potential period. 1 The gate of the second transistor that absorbs the infrared light and the second infrared light and changes the amount of charge accumulated in the second floating diffusion node by using the photocurrent output from the second photodiode. The potential of the electrode is set to a high potential while the first infrared light irradiation period and the first infrared light reflection period overlap, and the first infrared light in the high potential period is detected, whereby the first The detection signal S1 is acquired, and after the second infrared light irradiation, the second infrared light irradiation period and the second infrared light reflection period do not overlap each other, and a high potential is set. By detecting the second infrared light, the second detection signal S2 is acquired, and the first detection signal S1, the second detection signal S2, the first infrared light irradiation period T, and the speed of light c are used. By calculating the distance x from the light source to the detected object according to Equation (1), the third order of the detected object Distance image information can be acquired.

In the above, the comparison with the specific object pattern may be performed by calculating a correlation coefficient.

In the above, the comparison with the specific operation pattern may be performed by calculating a correlation coefficient.

In the above, the imaging device absorbs visible light and transmits infrared light, and includes a first photodiode having a first semiconductor layer that absorbs infrared light and a second photo diode having a second semiconductor layer that absorbs infrared light. A plurality of diodes are preferably provided. In addition, the first photodiode and the second photodiode are preferably provided so as to overlap each other.

In the above, amorphous silicon or polycrystalline silicon can be used for the first semiconductor layer.

In the above, polycrystalline silicon, microcrystalline silicon, or single crystal silicon can be used for the second semiconductor layer.

In the above, a silicon material may be used for the semiconductor layer of the first transistor.

In the above, a silicon material may be used for the semiconductor layer of the second transistor.

In the above, an oxide semiconductor material may be used for the semiconductor layer of the first transistor.

In the above, an oxide semiconductor material may be used for the semiconductor layer of the second transistor.

The above configuration solves at least one of the above problems.

In this specification, “object data” indicates shape information, position information, direction information, form information, type information, part information, and the like of an object to be detected including color information and brightness information. That is, information including 2D image information and 3D distance image information is shown. Therefore, the part of the detected object indicates, for example, “hand and hand color (skin color, etc.)”, “foot and foot color (skin color, etc.)” and the like.

Further, in this specification, “motion data” indicates a time change of “object data”. The time change information of the shape of the detection object, the time change information of the position, the time change information of the direction, the time change information of the form, and the like are shown.

Further, in this specification, “imaging data” refers to information acquired from a three-dimensional distance image of a detection object imaged by an imaging device. The three-dimensional distance image means a collection of distance information obtained by measuring the distance between each pixel mounted in the imaging device and the object to be detected at a certain time.

According to one embodiment of the present invention, by using a three-dimensional distance image sensor to which the TOF method is applied for a motion recognition device, position change information and shape change information of an object to be detected including color image information with a simple configuration. Etc. can be detected. In addition, accurate motion recognition can be performed without restricting the operation of the detected object and without selecting the state of the detected object. Further, even if the detected object moves at high speed, accurate motion recognition can be performed without restricting the operation of the detected object and without selecting the state of the detected object.

The figure explaining a motion recognition apparatus. The figure explaining a motion recognition apparatus. 4A and 4B illustrate a photosensor according to Embodiment 2. FIG. 6 illustrates a timing chart of a photosensor according to Embodiment 2. FIG. 6 illustrates a timing chart of a photosensor according to Embodiment 2. FIG. 10 illustrates a photosensor according to Embodiment 3; FIG. 6 illustrates a timing chart of a photosensor according to Embodiment 3. FIG. 6 illustrates a timing chart of a photosensor according to Embodiment 3. FIG. 6 illustrates a photosensor according to Embodiment 4; FIG. 6 illustrates a photosensor according to Embodiment 4; FIG. 10 illustrates a timing chart of a photosensor according to Embodiment 4; FIG. 10 illustrates a timing chart of a photosensor according to Embodiment 4; FIG. 6 illustrates a reading circuit. The figure explaining an example of a motion recognition apparatus. The figure explaining an example of a motion recognition apparatus. The figure explaining an example of a motion recognition apparatus. FIG. 6 is a circuit diagram of a plurality of photosensors arranged in a matrix. The top view and sectional drawing of a photosensor. Sectional drawing of a photosensor. Sectional drawing of a photosensor. FIG. 6 is a circuit diagram of a plurality of photosensors arranged in a matrix. FIG. 6 is a circuit diagram of a plurality of photosensors arranged in a matrix. FIG. 6 is a circuit diagram of a plurality of photosensors arranged in a matrix. The top view of a photosensor. Sectional drawing of a photosensor.

Embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below. Note that in structures of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description thereof is not repeated.

(Embodiment 1)
In this embodiment mode, a motion recognition device having an imaging device to which the TOF method is applied will be described with reference to FIGS.

Note that in one embodiment of the disclosed invention, motion recognition is performed based on pattern matching. Imaging data used for pattern matching is acquired from an imaging device. Compares the imaging data of the object to be detected that changes over time with various specific object patterns in the database, selects the best matching object data (pattern matching), and from the operation start time to the operation end time Is divided at specific time intervals, and the object data selected at each time is compared with various specific operation patterns in the database, and a method of estimating operation data (time change of object data) is employed. The motion recognition apparatus can perform an operation based on the output data generated from the motion data. In addition, since the imaging data includes three-dimensional distance image information and color image information, it is possible to improve the detection accuracy of the motion recognition apparatus by performing pattern matching using the imaging data.

The motion recognition device applies the TOF method and acquires imaging data from the imaging device. The TOF method irradiates the object to be detected with light (irradiated light), and when the light reflected by the object to be detected (reflected light) reaches the imaging device, the irradiated light reaches the object to be detected. In addition, the time until the reflected light arrives at the imaging device is detected, and the distance from the imaging device to the detected object is obtained by calculation. The distance x from the light source to the object to be detected can be expressed by the following equation x = (c × Δt) / 2. Here, c is the speed of light (3 × 10 ⁸ m / s), and Δt is the delay time.

The imaging apparatus acquires a plurality of distance information by measuring the distance between each pixel mounted in the display unit and the object to be detected. By collecting these distance information, distance image information can be acquired and acquired as imaging data.

Further, the imaging apparatus can perform two-dimensional imaging and three-dimensional imaging using the TOF method at a time. In this case, the imaging apparatus includes a first photosensor that absorbs visible light and a second photosensor that absorbs infrared light, and these sensors are preferably superimposed. By performing two-dimensional imaging using the first photosensor and performing three-dimensional imaging using the second photosensor, three-dimensional distance image information and color image information are simultaneously acquired, and these three-dimensional distance images are obtained. Information and color image information can be acquired as imaging data.

Since the TOF method is applied, the motion recognition apparatus can acquire the three-dimensional distance image information at a certain time without contacting the object to be detected.

In addition, the motion recognition device can acquire color image information at a certain time without contact with the object to be detected.

In addition, since the imaging device has a simple configuration, it can be installed in the display unit of the motion recognition device.

Furthermore, since the TOF method is applied, it is difficult to be affected by the state of the detected object such as heat and temperature, and the operation can be recognized without selecting the state of the detected object.

The light source is preferably mounted in the imaging device.

FIG. 1A is a block diagram illustrating an entire structure of a motion recognition device according to one embodiment of the disclosed invention. The motion recognition device 100 includes an imaging device 101, an image processing device 102, and an information processing device 103. The imaging data 104 is output from the imaging device 101 and input to the image processing device 102. The output data 105 is output from the image processing apparatus 102 and input to the information processing apparatus 103.

The image processing apparatus 102 includes an image storage unit 110, a first storage unit 111, a second storage unit 112, a third storage unit 113, a fourth storage unit 114, an object data detection unit 115, and an operation data detection unit 116. , And an output control unit 117. The first storage unit 111 stores a specific object pattern, and the second storage unit 112 stores a specific operation pattern. The reference specific object pattern and the specific operation pattern are stored in the database in advance.

The image storage unit 110 acquires the imaging data 104 from the imaging device 101 and stores it. The image storage unit 110 includes a storage unit for three-dimensional distance image information, and may include a storage unit for color image information. For example, two-dimensional information (brightness, color, etc. of an object to be detected) obtained by two-dimensional imaging of the imaging apparatus 101 is stored in a color image information storage unit, and three-dimensional distance image information (light source) obtained by three-dimensional imaging. To the object to be detected) is stored in the storage unit of the three-dimensional distance image information.

In the first storage unit 111, various specific object patterns are stored in advance. The specific object pattern corresponds to, for example, a fingertip shape pattern when detecting the movement of a person's finger as the object to be detected. Further, when detecting the movement of a person's hand as the object to be detected, this corresponds to the shape pattern of each fingertip or palm.

The specific object pattern may include color image information in addition to the three-dimensional distance image information. When color image information is included, for example, when detecting the movement of a person's finger as an object to be detected, information on finger color (skin color, etc.) and nail color (transparency, etc.) in addition to the fingertip shape pattern Etc. are also added. In addition, when detecting the movement of a person's hand as an object to be detected, information on the palm color (skin color, etc.) is added in addition to the fingertip and palm shape patterns.

In the second storage unit 112, various specific operation patterns are stored in advance. The specific operation pattern means a movement accompanied by movement or change of a region showing a specific state, a movement having a repeatability repeated at a constant cycle, a stroke, and the like. For example, it corresponds to moving a fingertip from the top to the bottom, performing a series of actions such as goo, choki, and par with a hand.

Note that the specific operation pattern may include color image information. When color image information is included, finger color (skin color, etc.) and nail color in addition to position change information and shape change information such as moving the fingertip from top to bottom, hand-going, choking, and parsing Information such as (transparency) is also added.

The imaging apparatus 101 captures an object to be detected and acquires a three-dimensional distance image of the object to be detected. It is also possible to acquire a color image. A distance measurement method based on the TOF method is used to acquire a three-dimensional distance image. According to the imaging apparatus 101, a three-dimensional distance image can be acquired with a simple configuration without using a large number of cameras or the like. The three-dimensional distance image and the color image are output as the imaging data 104 from the imaging device 101 to the image processing device 102. Note that the imaging apparatus 101 needs to be arranged at a position where the user who operates the motion recognition apparatus 100 can capture an image. The imaging device 101 may be installed in the display unit of the motion recognition device 100 or may be installed outside the motion recognition device 100.

Although the imaging data 104 changes with the passage of time, the imaging apparatus 101 can acquire the imaging data 104 at each time at specific time intervals. In this specification, the imaging data 104 at time t _n is referred to as imaging data 104_n.

The image processing apparatus 102 receives the imaging data 104 and generates output data 105 necessary for the information processing apparatus 103 to perform appropriate processing. The output data 105 is generated from the operation data. Appropriate processing means that the motion recognition device 100 performs an operation corresponding to the output data 105 without directly touching the operation unit of the motion recognition device 100 or the motion recognition device 100 itself. To do.

It should be noted that the operation of the motion recognition device 100 (for example, inputting 1 as the calling number of the mobile phone) and the motion data necessary for the motion recognition device 100 to perform the operation (for example, raising the index finger of the hand) ) Is determined in advance. When the output data 105 necessary for performing a desired operation is output from the image processing apparatus 102, the information processing apparatus 103 can perform appropriate processing.

In addition, in the operation recognition in this specification, a database prepared in advance is used. In the database, in addition to the specific object pattern and the specific motion pattern of the object to be detected, the motion data necessary for performing a certain operation, that is, which motion data is used to perform a certain operation. It is also registered. In addition, data generated using various patterns acquired by the motion recognition apparatus 100 can be additionally registered in the database.

The information processing apparatus 103 receives the output data 105 and performs a process on the operation recognition apparatus 100 so that an operation corresponding to the output data 105 is executed. The operation corresponding to the output data 105 means that the motion recognition apparatus 100 is operated in correspondence with the motion of the detected object. Since the motion recognition apparatus 100 can be applied to various applications, the information processing apparatus 103 needs to perform processing corresponding to each application using the output data 105. For example, when the motion recognition apparatus 100 is applied to a gas stove, the process corresponding to the application will turn on the stove if the fingertip is moved from top to bottom, and the fire on the stove will disappear if the fingertip is moved from bottom to top. It means a process in which such an operation is executed.

Next, operation recognition performed in the image processing apparatus 102 will be described in detail. FIG. 2 is a flowchart illustrating a flow of motion recognition in one embodiment of the disclosed invention.

In the image storage unit 110, the operation of step 301 is performed. In step 301, the image storage unit 110 stores the imaging data 104_n at time t _n (n is a natural number).

The object data detection unit 115 performs operations from step 302 to step 309. First, in step 302, a specific object pattern is extracted from the imaging data 104_n.

Next, in step 303, the specific object pattern extracted from the imaging data 104_n is compared with the specific object pattern stored in the first storage unit 111.

Next, in step 304, a correlation coefficient is calculated, and a specific object pattern that most closely matches the feature is selected from various specific object patterns in the database on the basis of the correlation coefficient. When the correlation coefficient (α) is equal to or greater than a certain value (β) as in step 305, the process proceeds to step 306. In step 306, it is assumed that a specific object pattern that matches the object pattern extracted from the imaging data 104_n exists among the various specific object patterns stored in the first storage unit 111. If the correlation coefficient (α) is smaller than a certain value (β) as in step 308, the process proceeds to step 309. In step 309, it is assumed that there is no specific object pattern that matches the object pattern extracted from the imaging data 104_n among the various specific object patterns stored in the first storage unit 111.

If the process proceeds to step 306, the object data detecting section 115 in step 307 obtains the object data at the time t _n (also referred to as n-th data).

In the third storage unit 113, the operation of step 310 is performed. In step 310, a third storage unit 113 stores object data at time _{t n.} The object data changes with the passage of time, but can be acquired each time. For example, it is possible to acquire first object data at time t ₁ and acquire third object data at time t ₃ .

In order to obtain object data continuously, the process may return from step 310 to step 301 again. For example, sequentially from time _{t 1} to time _{t 10,} if the first object data to obtain a tenth object data may be repeated 10 times from step 301 to step 306.

The operation data detection unit 116 performs operations from step 311 to step 317. First, in step 311, the time change of the object data is compared with the specific operation pattern stored in the second storage unit 112.

Next, in step 312, a correlation coefficient is calculated, and a specific action pattern that most closely matches the feature is selected from various specific action patterns in the database with reference to the correlation coefficient. If the correlation coefficient (γ) is greater than or equal to a certain value (δ) as in step 313, the process proceeds to step 314. In step 314, the various specific operation patterns stored in the second storage unit 112 are considered to be equal to the time change of the object data. If the correlation coefficient (γ) is smaller than a certain value (δ) as in step 316, the process proceeds to step 317. In step 317, various specific operation patterns stored in the second storage unit 112 are considered to be different from the temporal change of the object data. That is, the specific operation pattern is compared with the time change of the object data to determine whether the specific operation pattern has been performed or not.

Note that the reference value δ of the correlation coefficient may differ depending on the content of processing performed by the information processing apparatus 103 thereafter. The information processing apparatus 103 that defines the processing content includes a table in which the temporal change of the object data and the reference value δ of the correlation coefficient are associated as additional data, so that the information processing apparatus 103 reads the information appropriately when the information processing apparatus 103 is started up. It is good to make it.

In step 315, when the various specific motion patterns stored in the second storage unit 112 match the time change of the object data, the motion data detection unit 116 acquires motion data.

In the fourth storage unit 114, the operation of Step 318 is performed. In step 318, the fourth storage unit 114 stores the operation data.

In the output control unit 117, the operation of step 319 is performed. In step 319, the output control unit 117 generates output data 105 from the operation data stored in the fourth storage unit 114 and outputs the output data 105 to the information processing apparatus 103. The output control unit 117 may not only generate the output data 105 but also supply appropriate data to the information processing apparatus 103 according to each application.

According to the motion recognition apparatus 100 using the above configuration, the motion of the detected object can be recognized without contact with the detected object performing the motion. In addition, it has a simple configuration and can perform accurate motion recognition without selecting the state of the object to be detected.

According to the motion recognition apparatus 100 using the above configuration, it is possible to detect color image information in addition to position change information, shape change information, and the like of an object to be detected. In this case, detection accuracy can be further improved.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 2)
In this embodiment, an example of a method for driving an imaging device to which the TOF method is applied is described with reference to FIGS. More specifically, the first imaging and the second imaging are performed in correspondence with the first irradiation period and the second irradiation period (timing is different at the same irradiation time), and the first reflection is performed. The first detection signal depending on the light delay time is obtained from the reflected light detection of one, and the second detection signal depending on the light delay time is obtained from the second reflected light detection by the second reflection. Thus, an example of a method for driving the imaging apparatus that measures the distance from the light source to the object to be detected will be described.

The photosensor included in the imaging device in this embodiment includes three transistors and one photodiode. FIG. 3 is an example of a circuit diagram illustrating a configuration of the photosensor 400 included in the imaging device. The photosensor 400 includes a photodiode 402, a transistor 403, a transistor 404, and a transistor 405.

The signal line 11 is a reset signal line (PR). The signal line 12 is a charge accumulation signal line (TX). The signal line 13 is a selection signal line (SE). Node 14 is a floating diffusion (FD) node. The signal line 15 is a photosensor reference signal line. The signal line 16 is a photosensor output signal line.

In the photosensor 400, the anode of the photodiode 402 is electrically connected to the signal line 11, and the cathode of the photodiode 402 is electrically connected to one of the source electrode and the drain electrode of the transistor 403. The other of the source electrode and the drain electrode of the transistor 403, the gate electrode of the transistor 404, and the node 14 are electrically connected. One of the source electrode and the drain electrode of the transistor 404 and the signal line 15 are electrically connected. One of a source electrode or a drain electrode of the transistor 405 and the signal line 16 are electrically connected. The other of the source and drain electrodes of the transistor 404 and the other of the source and drain electrodes of the transistor 405 are electrically connected. The gate electrode of the transistor 403 and the signal line 12 are electrically connected, and the gate electrode of the transistor 405 and the signal line 13 are electrically connected.

Note that FIG. 3 illustrates a structure in which the anode of the photodiode 402 is electrically connected to the signal line 11 and the cathode of the photodiode 402 is electrically connected to one of the source electrode and the drain electrode of the transistor 403. However, it is not limited to this. The cathode of the photodiode 402 may be electrically connected to the signal line 11, and the anode of the photodiode 402 may be electrically connected to one of the source electrode and the drain electrode of the transistor 403.

The photodiode 402 is a photoelectric conversion element that generates current when irradiated with light. Accordingly, a photocurrent flows through the photodiode 402 by detecting the light reflected from the object to be detected.

The transistor 403 functions as a transistor that controls the imaging time. In one embodiment of the disclosed invention, the potential of the signal line 11 is switched from “L (Low)” to “H (High)”, and the potential of the gate electrode of the transistor 403 (the potential of the signal line 12) is changed to “L (Low)”. When switching from “H” to “H”, positive charges are accumulated in the node 14. When the potential of the signal line 11 is switched from “H” to “L” while the potential of the gate electrode of the transistor 403 (the potential of the signal line 12) is maintained at “H”, imaging starts and the photodiode 402 is irradiated. Negative charges are accumulated in the node 14 in accordance with the emitted light. The end of imaging is when the potential of the gate electrode of the transistor 403 (the potential of the signal line 12) is switched from “H” to “L”.

In the present embodiment, in the first imaging, the signal line 11 and the signal line 12 are set so that the first imaging starts at the same time as the first irradiation starts and the first imaging ends at the same time as the first irradiation ends. To control the potential. Further, in the second imaging, the second imaging starts at the same time as the second irradiation ends, and the second imaging ends after the imaging at the same time as the first imaging. Control the potential.

That is, the potential of the gate electrode of the transistor 403 is set to “H” while the first irradiation period and the first reflection period overlap, and the second irradiation period and the second reflection period after the start of the second irradiation are set. Control may be performed such that “H” is set while they do not overlap and “H” is set in the first reflected light detection period and the second reflected light detection period.

The transistor 404 functions as a transistor that amplifies the charge accumulated in the node 14. The transistor 405 functions as a transistor that controls the output of the photosensor. When the signal (the potential of the signal line 13) input to the gate electrode of the transistor 405 is switched from “L” to “H”, the signal is read out.

As described above, the photosensor 400 includes four elements, that is, one photodiode and three transistors. Since the photosensor can be configured with a small number of elements, it is easy to integrate the photosensors with high density and achieve miniaturization of pixels.

Note that as the semiconductor layer used for the transistor 403, an oxide semiconductor layer is preferably used. In order to hold the charge generated by irradiating the photodiode 402 with light for a long time, the transistor 403 electrically connected to the photodiode needs to be formed using a transistor with extremely low off-state current. . A transistor including an oxide semiconductor material has extremely low off-state current. Therefore, the performance of the photosensor 400 can be improved by using an oxide semiconductor material for the semiconductor layer.

In addition, it is possible to suppress the flow of charge that leaks from the node 14 to the photodiode 402. In particular, when the time difference generated between the first imaging and the second imaging is large, that is, when it takes a long time to accumulate the charge in the node 14, the influence of the leakage charge becomes large. It is particularly preferable to use a semiconductor material. Using an oxide semiconductor material as a semiconductor layer, light irradiated from a light source (irradiated light) arrives at the object to be detected, and further, light reflected by the object to be detected (reflected light) arrives at the imaging device. It is also possible to improve the performance of the entire photosensor 400 by detecting time with higher accuracy and acquiring highly reliable imaging data.

Further, in the case where it is important to store charges generated by irradiating the photodiode 402 with light in the node 14 in a short time, amorphous silicon, microcrystalline silicon, multi-layer silicon, or the like is used as a semiconductor layer used in the transistor 403. Materials such as crystalline silicon and single crystal silicon can also be used. By using these materials, a transistor with high mobility can be formed, so that charges can be accumulated in the node 14 in a short time.

As the semiconductor layer used for the transistor 404, a material such as polycrystalline silicon or single crystal silicon is preferably used. By using a semiconductor layer with high mobility, the amplification degree with respect to the charge accumulated in the node 14 can be increased, so that an amplification transistor with higher sensitivity can be configured.

As a semiconductor layer used for the transistor 405, a material such as polycrystalline silicon or single crystal silicon is preferably used. By using these materials, the on-state current of the transistor 405 can be increased. Therefore, the data reading time can be shortened and the output of the photosensor can be controlled at high speed. Further, by using a semiconductor layer having high mobility, the switching speed of the signal line 16 can be controlled in a wider range. By increasing the degree of freedom of the speed of potential change and clearly extracting the speed difference, more accurate data can be acquired.

An example of a method for driving an imaging device including the photosensor 400 will be described. By using this driving method, it is possible to measure a three-dimensional distance image by three-dimensional imaging using the TOF method.

A specific driving method will be described with reference to timing charts shown in FIGS. First, the operation of the photosensor 400 will be described with reference to FIG. Next, with reference to FIG. 5, the characteristics of the driving method and a three-dimensional distance image measurement method by three-dimensional imaging using the TOF method will be described.

In the timing charts shown in FIGS. 4 and 5, “irradiation” is represented by “H” and “non-irradiation” is represented by “L” in the pulses 501 and 502, and the potential is high in other pulses. The state is represented by “H”, and the low potential state is represented by “L”.

FIG. 4 is a timing chart of the photosensor 400. Between time T1 and time T15, irradiation (first irradiation and second irradiation) is performed twice from the light source to the detected object. Note that the second irradiation is different in timing from the first irradiation and is performed for the same time. In the first irradiation and the second irradiation, the distance between the light source and the object to be detected is not changed, and the time from time T2 to time T3 (delay time) and the time from time T8 to time T9 (delay) It is obvious that time is equal.

At time T1, the signal line 11 is set to “H”. Further, the signal line 12 is set to “H” (first reset). At this time, the photodiode 402 and the transistor 403 are turned on, and the node 14 becomes “H”.

At time T2, irradiation of the first light from the light source to the object to be detected is started. The pulse 501 changes from “L” (non-irradiation) to “H” (irradiation). Let this time be the first irradiation start time. Further, the signal line 11 is set to “L”, and the signal line 12 is maintained at “H” (first imaging starts). Note that the first imaging start time coincides with the first irradiation start time.

At time T3, the first irradiation light emitted from the light source is reflected by the detection object, and the first reflected light starts to enter the imaging apparatus. The pulse 502 changes from “L” (non-irradiation) to “H” (irradiation). Let this time be the first reflection start time.

Time T3 is also the first reflected light detection start time. Detection of reflected light can be started at time T3.

Between time T3 and time T4 (first reflected light detection, so-called net first imaging), the potential of the node 14 changes according to the intensity of the first reflected light. Due to the off-state current of the photodiode 402, the potential of the node 14 starts to be lower than “H”. The off-current is proportional to the intensity of light (reflected light) irradiated on the photodiode 402 and the irradiation time.

Here, the relationship between the potential change of the node 14, the intensity of light (reflected light) irradiated on the photodiode 402, and the irradiation time will be described. In the same detection period, the greater the reflected light intensity, the greater the potential change at the node 14. For the same intensity, the longer the reflected light detection period, the greater the potential change at the node 14. Therefore, the greater the reflected light intensity and the longer the reflected light detection period, the greater the off-current of the photodiode 402 and the greater the potential change at the node 14.

At time T4, the irradiation of the first light from the light source to the detected object is terminated. The pulse 501 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the first irradiation end time. The signal line 12 is set to “L”. At this time, the first imaging is finished. Note that the first imaging end time coincides with the first irradiation end time. Time T4 is also the first reflected light detection end time.

As described above, the potentials of the signal line 11 and the signal line 12 are controlled so that the first imaging is started simultaneously with the start of the first irradiation and the first imaging is ended simultaneously with the end of the first irradiation.

Note that the potential of the node 14 is constant after the time T4. The potential (V1) of the node 14 at time T4 depends on the photocurrent generated by the photodiode 402 during the first reflected light detection. That is, it is determined according to the reflected light intensity or the like.

Further, the first detection signal is determined in accordance with the potential (V1) of the node 14 at the time T4. As the first reflected light detection period is longer, the potential change of the node 14 is larger, so the potential (V1) of the node 14 at time T4 is smaller.

Note that light irradiated to the photodiode 402 between time T1 and time T4 indicates all first reflected light. That is, it refers to light that is irradiated from the light source to the detected object and reflected from the detected object.

At time T5, the first reflected light reflected by the object to be detected is incident on the imaging device. In the pulse 502, “H” (irradiation) changes to “L” (non-irradiation). This time is set as the first reflection end time.

Note that when the signal line 12 is set to “L”, the potential of the node 14 changes due to the parasitic capacitance between the signal line 12 and the node 14. When the potential change is large, the photodiode 402 cannot accurately acquire the generated photocurrent in the first imaging. Therefore, in order to reduce the influence of the parasitic capacitance, measures such as reducing the capacitance between the gate electrode and the source electrode of the transistor 403 or the capacitance between the gate electrode and the drain electrode of the transistor 403, or connecting a storage capacitor to the node 14 are taken. It is valid. In the photosensor 400 according to one embodiment of the present invention, these countermeasures are taken so that a change in potential of the node 14 due to parasitic capacitance can be ignored.

At time T6, the signal line 13 is set to “H” (first reading start). At this time, the transistor 405 becomes conductive. In addition, the signal line 15 and the signal line 16 are brought into conduction through the transistor 404 and the transistor 405. As a result, the potential of the signal line 16 decreases. Prior to time T6, the signal line 16 is precharged in advance and set to “H”.

The configuration of the readout circuit that performs the precharge operation on the signal line 16 is not particularly limited. The readout circuit can also be constituted by one Pch transistor 406 as in the readout circuit 401 shown in FIG. The signal line 17 is a precharge signal line. The node 18 is a high potential supply line. A gate electrode of the transistor 406 is electrically connected to the signal line 17, one of a source electrode or a drain electrode of the transistor 406 is electrically connected to the signal line 16, and the other of the source electrode or the drain electrode of the transistor 406 is Are electrically connected to the node 18.

At time T7, the signal line 13 is set to “L” (end of the first reading). Then, the transistor 405 is cut off, and the potential of the signal line 16 becomes constant. The potential (V _S1 ) of the signal line 16 at time T7 depends on the speed of change in potential of the signal line 16 from time T6 to time T7.

Note that the speed of the potential change of the signal line 16 depends on the current between the source electrode and the drain electrode of the transistor 404. That is, it depends on the intensity (irradiation time) of light (reflected light) irradiated to the photodiode 402 in the first imaging. For the same irradiation time, the higher the reflected light intensity, the slower the potential change speed of the signal line 16. For the same intensity, the longer the reflected light detection period, the slower the potential change speed of the signal line 16. The slower the potential change rate of the signal line 16, the greater the potential (V _S1 ) of the signal line 16 at time T7.

Therefore, by acquiring the potential (V _S1 ) of the signal line 16 at time T7 by detecting the first reflected light, the amount of light (reflected light) incident on the photodiode 402 during the first imaging period (incided) The detection signal S1 can be obtained by detecting the time product of light intensity. Here, assuming that the intensity of light in the first irradiation is constant and only the first reflected light is incident, the potential (V _S1 ) of the signal line 16 is approximately proportional to the first reflected light detection period.

A relationship between the potential of the node 14 and the potential of the signal line 16 will be described. When the intensity of light (reflected light) applied to the photodiode 402 is large, the potential change of the node 14 within a certain period increases (the potential value of the node 14 at time T4 decreases). At this time, since the channel resistance of the transistor 404 is increased, the potential change speed of the signal line 16 is decreased. Therefore, the potential change of the signal line 16 within a certain period is small (the value of the potential of the signal line 16 at time T7 is high).

At time T8, irradiation of the second light from the light source to the object to be detected is started. The pulse 501 changes from “L” (non-irradiation) to “H” (irradiation). This time is set as the second irradiation start time.

At time T9, the second irradiation light emitted from the light source is reflected by the detection object, and the second reflected light starts to enter the imaging apparatus. The pulse 502 changes from “L” (non-irradiation) to “H” (irradiation). This time is set as the second reflection start time.

At time T10, the signal line 11 is set to “H”, and the signal line 12 is set to “H” (second reset). At this time, the photodiode 402 and the transistor 403 are turned on, and the node 14 becomes “H”.

At time T11, the irradiation of the second light from the light source to the detected object is terminated. The pulse 501 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the second irradiation end time. The signal line 11 is set to “L”, and the signal line 12 is maintained at “H” (second imaging starts). Note that the second imaging start time coincides with the second irradiation end time. The time T11 is also the second reflected light detection start time.

Between time T11 and time T12 (second reflected light detection, so-called net second imaging), the potential of the node 14 changes according to the intensity of the second reflected light. Due to the off-state current of the photodiode 402, the potential of the node 14 starts to be lower than “H”. The off-current is proportional to the intensity of light (reflected light) irradiated on the photodiode 402 and the irradiation time. Therefore, the potential of the node 14 also changes depending on the reflected light intensity and the reflected light detection period.

In the present embodiment, as an example, the second reflected light detection period (time T11 to time T12) is shorter than the first reflected light detection period (time T3 to time T4). Yes. For this reason, the potential change of the node 14 during the second imaging is smaller than the potential change of the node 14 during the first imaging.

At time T12, the second reflected light reflected by the object to be detected is incident on the imaging device. In the pulse 502, “H” (irradiation) changes to “L” (non-irradiation). This time is set as the second reflection end time. The time T12 is also the second reflected light detection end time.

Note that the potential of the node 14 is constant after time T12. The potential (V2) of the node 14 at time T12 depends on the photocurrent generated by the photodiode 402 during the second reflected light detection. That is, it is determined according to the reflected light intensity or the like.

Further, the second detection signal is determined in accordance with the potential (V2) of the node 14 at the time T12. The shorter the second reflected light detection period, the smaller the potential change of the node 14, and thus the potential (V 2) of the node 14 at time T 12 becomes larger.

At time T13, the signal line 12 is set to “L”. At this time, the second imaging is finished.

As described above, the potential of the signal line 11 and the signal line 12 is controlled so that the second imaging is started simultaneously with the end of the second irradiation, and the second imaging is ended after the imaging at the same time as the first imaging. .

Note that light irradiated on the photodiode 402 between time T10 and time T13 is all pointing to second reflected light. That is, the light is irradiated from the light source to the object to be detected, and the light reflected from the object to be detected is indicated.

At time T14, the signal line 13 is set to “H” (second read start). At this time, the transistor 405 becomes conductive. In addition, the signal line 15 and the signal line 16 are brought into conduction through the transistor 404 and the transistor 405. As a result, the potential of the signal line 16 decreases. Prior to time T14, the signal line 16 is precharged in advance and set to “H”.

At time T15, the signal line 13 is set to “L” (end of second reading). Then, the transistor 405 is cut off, and the potential of the signal line 16 becomes constant. The potential (V _S2 ) of the signal line 16 at time T15 depends on the speed of change in potential of the signal line 16 from time T14 to time T15.

If the light intensity is the same, the shorter the reflected light detection period, the faster the potential change speed of the signal line 16. The faster the potential change rate of the signal line 16, the smaller the potential (V _S2 ) of the signal line 16 at time T15.

Therefore, by acquiring the potential (V _S2 ) of the signal line 16 at time T15 by detecting the second reflected light, the amount of light (reflected light) incident on the photodiode 402 during the second imaging period (incided) The detection signal S2 can be obtained by detecting the time product of light intensity. Here, assuming that the intensity of light in the second irradiation is constant and only the second reflected light is incident, the potential (V _S2 ) of the signal line 16 is approximately proportional to the second reflected light detection period.

In the present embodiment, since the second reflected light detection period (time T11 to time T12) is shorter than the first reflected light detection period (time T3 to time T4), the signal line at time T15. 16 potential (V _S2 ) is smaller than the potential (V _S1 ) of the signal line 16 at time T7.

FIG. 5 shows potentials of the pulse 501, the pulse 502, and the signal line 12 in the photosensor 400. First, the characteristics of the driving method will be described with reference to FIG. In order to perform the first reflected light detection and the second reflected light detection, the driving method according to one embodiment of the disclosed invention is that the potential of the signal line 11 and the signal line 12 is controlled to devise the timing of the imaging time. Is the main feature.

While comparing the pulses shown in FIG. 5, description will be made separately for each period such as an irradiation period, a reflection period, an imaging period, an accumulation operation period, and a reflected light detection period.

As shown in the pulse 501, time T2 is the first irradiation start time, time T4 is the first irradiation end time, and time T2 to time T4 is the first irradiation period. Time T8 is the second irradiation start time, time T11 is the second irradiation end time, and time T8 to time T11 are the second irradiation period. In one embodiment of the disclosed invention, the first irradiation period and the second irradiation period are necessarily equal.

As indicated by the pulse 502, time T3 is the first reflection start time, time T5 is the first reflection end time, and time T3 to time T5 are the first reflection period. Time T9 is the second reflection start time, time T12 is the second reflection end time, and time T9 to time T12 are the second reflection period. The reflection period is equal to the irradiation period.

That is, the first irradiation period and the second irradiation period are equal, and the first reflection period and the second reflection period are equal.

As shown by the potential of the signal line 12, time T1 is the first accumulation operation start time, time T4 is the first accumulation operation end time, and time T1 to time T4 are the first accumulation operation period. Time T2 is the first imaging start time, time T4 is the first imaging end time, and time T2 to time T4 are the first imaging period. Time T3 is the first reflected light detection start time, time T4 is the first reflected light detection end time, and time T3 to time T4 are the first reflected light detection period.

The first accumulation operation period must be started at least before the first reflection period. Further, the first accumulation operation period (first imaging) must end at the same time as the end of the first irradiation period. In this way, the potentials of the signal line 11 and the signal line 12 are controlled so that the timing of the imaging period is determined.

Further, as shown by the potential of the signal line 12, time T10 is the second accumulation operation start time, time T13 is the second accumulation operation end time, and time T10 to time T13 are the second accumulation operation period. is there. Time T11 is the second imaging start time, time T13 is the second imaging end time, and time T11 to time T13 are the second imaging period. Time T11 is the second reflected light detection start time, time T12 is the second reflected light detection end time, and time T11 to time T12 are the second reflected light detection period.

The second accumulation operation period (second imaging) must be started simultaneously with the end of the second irradiation period. In addition, the second accumulation operation period must end at least after the second reflection period. In this way, the potentials of the signal line 11 and the signal line 12 are controlled so that the timing of the imaging period is determined.

That is, the first imaging period is determined corresponding to the first reflection period, and the second imaging period is determined corresponding to the second reflection period, so that the reflected light detection is separated twice. To do.

The first reflected light detection period is equal to a period in which the first irradiation period and the first reflection period overlap, and is a net first imaging period. Further, the second reflected light detection period is equal to the second reflection period after the second irradiation period, and is a net second imaging period. Then, a first detection signal depending on the light delay time is obtained from the first reflected light detection, and a second detection signal depending on the light delay time is obtained from the second reflected light detection. Thus, the distance from the imaging device to the object to be detected can be measured.

Next, a distance measurement method using three-dimensional imaging using the TOF method will be described. Imaging using the first detection signal S1 that depends on the delay time of the light acquired from the first reflected light detection and the second detection signal S2 that depends on the delay time of the light acquired from the second reflected light detection A method for measuring the distance from the apparatus to the object to be detected will be described using a calculation formula.

Here, the intensity of light in the first irradiation and the second irradiation is constant, and the first reflected light and the second reflected light are applied to the photodiode 402 during the first imaging period and the second imaging period, respectively. If the signal line 16 is incident only, the potential (V _S1 ) of the signal line 16 is approximately proportional to the first reflected light detection period, and the potential (V _S2 ) of the signal line 16 is approximately proportional to the second reflected light detection period. To do.

That is, the first detection signal S1 obtained by the first imaging generally depends on the first reflected light detection period, and the second detection signal S2 obtained by the second imaging is the second reflected light detection. It largely depends on the period.

The first detection signal S1 and the second detection signal S2 can be expressed by equations (2) and (3), respectively, using a proportional constant α, an irradiation period T, and a delay time Δt.

When the proportionality constant α is eliminated from the equations (2) and (3), the delay time Δt is obtained as shown in the equation (4).

Furthermore, using the above-described equation (x = (c × Δt) / 2) for the distance x from the light source to the object to be detected and Equation (4), the distance x from the imaging device to the object to be detected It can be represented by (1).

Thus, if the first detection signal S1 and the second detection signal S2 are obtained, the distance x from the imaging device to the detected object can be obtained.

Alternatively, the third imaging may be performed by the photosensor 400 during a period in which light irradiation from the light source is not performed. In this case, the third detection signal S3 is obtained by the third imaging. The third detection signal S3 is subtracted from the first detection signal S1, and further, the third detection signal S3 is subtracted from the second detection signal S2, and these are renewed to detect the detection signal S1 and the detection in Equation (1) above. By using the signal S2, the influence of natural light can be removed.

Thus, a photosensor is configured with a small number of elements, and by devising a driving method in an imaging apparatus equipped with the photosensor, three-dimensional imaging using the TOF method can be realized, and the function as a distance image measuring apparatus can be realized. You can see that you can do it. Therefore, it is possible to solve the problem that the number of elements of the photosensor generated when the TOF method is applied, and to realize an imaging apparatus having a simple configuration.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 3)
In this embodiment, an example of a method for driving an imaging device to which the TOF method is applied is described with reference to FIGS. According to the driving method, it is possible to detect the position with high accuracy even when the detection object moves at high speed. More specifically, the reflected light at the same point of the object to be detected is detected by the adjacent photosensors. One photosensor performs first imaging to detect reflected light from the object to be detected when the object is irradiated with light. The other photosensor performs second imaging to detect reflected light from the detected object after the end of light irradiation on the detected object. By performing the first imaging and the second imaging continuously, no time difference is caused between the end of the first imaging and the start of the second imaging. According to this method, the detection accuracy can be improved even when the object to be detected moves at high speed.

A photosensor included in an imaging device of one embodiment of the invention disclosed in this specification includes three transistors and one photodiode. FIG. 6 is an example of a circuit diagram illustrating structures of the photosensor 700_n and the photosensor 700_ (n + 1) included in the imaging device. Note that an example in which the photosensor 700_n and the photosensor 700_ (n + 1) have the same structure is described.

As illustrated in FIG. 6, the photosensor 700_n and the photosensor 700_ (n + 1) are adjacent to each other. The photosensor 700 — n includes three transistors and one photodiode. Similarly, the photosensor 700_ (n + 1) includes three transistors and one photodiode.

As illustrated in FIG. 6, the photosensor 700 — n includes a photodiode 702 — n, a transistor 703 — n, a transistor 704 — n, and a transistor 705 — n. The photosensor 700_ (n + 1) includes a photodiode 702_ (n + 1), a transistor 703_ (n + 1), a transistor 704_ (n + 1), and a transistor 705_ (n + 1).

Note that in one embodiment of the disclosed invention, irradiation of light from a light source to an object to be detected is performed only once. Therefore, the reflected light incident on the photosensor from the object to be detected indicates the reflected light corresponding to one irradiation.

Here, in the adjacent photo sensor 700_n and photo sensor 700_ (n + 1), reflected light from substantially the same point of the detection object is incident on the photo sensor 700_n and the photo sensor 700_ (n + 1).

That is, the reflected light incident on the photodiode 702_n and the reflected light incident on the photodiode 702_ (n + 1) are reflected at the same point of the object to be detected when the object is irradiated from the light source. Light.

In FIG. 6, a signal line 11_n is a reset signal line (PR_n). The signal line 12_n is a charge accumulation signal line (TX_n). The signal line 13_n is a selection signal line (SE_n). The node 14_n is a floating diffusion (FD) node. The signal line 16_n is a photosensor output signal line (OUT_n).

In FIG. 6, a signal line 11_ (n + 1) is a reset signal line (PR_ (n + 1)). The signal line 12_ (n + 1) is a charge accumulation signal line (TX_ (n + 1)). The signal line 13_ (n + 1) is a selection signal line (SE_ (n + 1)). The node 14_ (n + 1) is a floating diffusion (FD) node. The signal line 16_ (n + 1) is a photosensor output signal line (OUT_ (n + 1)). The signal line 15 is a photosensor reference signal line, and can be shared by the photosensor 700_n and the photosensor 700_ (n + 1).

As illustrated in FIG. 6, in the photosensor 700_n, the anode of the photodiode 702_n is electrically connected to the signal line 11_n, and the cathode of the photodiode 702_n is electrically connected to one of the source electrode and the drain electrode of the transistor 703_n. ing. The other of the source electrode and the drain electrode of the transistor 703 — n, the gate electrode of the transistor 704 — n, and the node 14 — n are electrically connected. One of a source electrode and a drain electrode of the transistor 704 — n and the signal line 15 are electrically connected. One of a source electrode and a drain electrode of the transistor 705 — n and the signal line 16 — n are electrically connected. The other of the source and drain electrodes of the transistor 704 — n and the other of the source and drain electrodes of the transistor 705 — n are electrically connected. The gate electrode of the transistor 703 — n and the signal line 12 — n are electrically connected, and the gate electrode of the transistor 705 — n and the signal line 13 — n are electrically connected.

Similarly, as illustrated in FIG. 6, in the photosensor 700_ (n + 1), the anode of the photodiode 702_ (n + 1) is electrically connected to the signal line 11_ (n + 1), and the cathode of the photodiode 702_ (n + 1) is , Is electrically connected to one of a source electrode and a drain electrode of the transistor 703_ (n + 1). The other of the source electrode and the drain electrode of the transistor 703_ (n + 1), the gate electrode of the transistor 704_ (n + 1), and the node 14_ (n + 1) are electrically connected. One of a source electrode and a drain electrode of the transistor 704_ (n + 1) and the signal line 15 are electrically connected. One of a source electrode and a drain electrode of the transistor 705_ (n + 1) and the signal line 16_ (n + 1) are electrically connected. The other of the source electrode and the drain electrode of the transistor 704_ (n + 1) is electrically connected to the other of the source electrode and the drain electrode of the transistor 705_ (n + 1). The gate electrode of the transistor 703_ (n + 1) and the signal line 12_ (n + 1) are electrically connected, and the gate electrode of the transistor 705_ (n + 1) and the signal line 13_ (n + 1) are electrically connected.

Note that FIG. 6 illustrates a structure in which the anode of the photodiode 702 — n is electrically connected to the signal line 11 — n and the cathode of the photodiode 702 — n is electrically connected to one of the source electrode and the drain electrode of the transistor 703 — n. However, it is not limited to this. The cathode of the photodiode 702 — n may be electrically connected to the signal line 11 — n, and the anode of the photodiode 702 — n may be electrically connected to one of the source electrode and the drain electrode of the transistor 703 — n.

Similarly, the anode of the photodiode 702_ (n + 1) is electrically connected to the signal line 11_ (n + 1), and the cathode of the photodiode 702_ (n + 1) is electrically connected to one of the source electrode and the drain electrode of the transistor 703_ (n + 1). However, the present invention is not limited to this. The cathode of the photodiode 702_ (n + 1) is electrically connected to the signal line 11_ (n + 1), and the anode of the photodiode 702_ (n + 1) is electrically connected to one of the source electrode and the drain electrode of the transistor 703_ (n + 1). May be.

The photodiode 702 is a photoelectric conversion element that generates current when irradiated with light. Therefore, a photocurrent flows through the photodiode 702 by detecting the light reflected from the object to be detected.

The transistor 703 functions as a transistor that controls imaging time. In one embodiment of the disclosed invention, the potential of the signal line 11 is switched from “L” to “H”, and the potential of the gate electrode of the transistor 703 (the potential of the signal line 12) is switched from “L” to “H”. Then, positive charges are accumulated in the node 14. When the potential of the signal line 11 is switched from “H” to “L” while the potential of the gate electrode of the transistor 703 (the potential of the signal line 12) is maintained at “H”, imaging starts and the photodiode 702 is irradiated. Negative charges are accumulated in the node 14 in accordance with the emitted light. As described above, the transistor 703 can change the amount of charge accumulated in the node 14 by setting the potential of the gate electrode to “H” or “L”. The end of imaging is when the potential of the gate electrode of the transistor 703 (the potential of the signal line 12) is switched from “H” to “L”.

In three-dimensional imaging, the potential of the signal line 11_n (PR_n) and the signal line 12_n (TX_n) is controlled. In addition, the potentials of the signal line 11_ (n + 1) (PR_ (n + 1)) and the signal line 12_ (n + 1) (TX_ (n + 1)) are controlled.

Specifically, in the first imaging, the signal lines 11_n (PR_n) and the signal lines 12_n (TX_n) are set so that the first imaging starts at the start of irradiation and the first imaging ends at the end of irradiation. Control the potential. In the second imaging, the signal line 11_ (n + 1) (PR_ (n + 1) is set so that the second imaging starts at the same time as the irradiation ends and the second imaging ends after the imaging at the same time as the first imaging. ) And the signal line 12_ (n + 1) (TX_ (n + 1)).

The transistor 704 functions as a transistor that amplifies the charge accumulated in the node 14. The transistor 705 functions as a transistor that controls the output of the photosensor. When the signal (the potential of the signal line 13) input to the gate electrode of the transistor 705 is switched from “L” to “H”, the signal is read.

As described above, the photosensor 700_n and the photosensor 700_ (n + 1) include four elements of one photodiode and three transistors. Since the photosensor can be configured with a small number of elements, it is easy to integrate the photosensors with high density and achieve miniaturization of pixels.

The transistors 703, 704, and 705 have functions similar to those of the transistors 403, 404, and 405 described in the above embodiment, respectively. Therefore, the above embodiment can be referred to for a semiconductor layer which is preferably used.

As described above, the photosensor includes four elements, one photodiode and three transistors. Since the photosensor can be configured with a small number of elements, it is easy to integrate the photosensors with high density and achieve miniaturization of pixels.

In the case of obtaining a small-sized photosensor that places particular emphasis on high-speed operation, all of the transistors 703, 704, and 705 can be formed of a material such as polycrystalline silicon or single crystal silicon.

In the case where cost reduction is important, all of the transistors 703, 704, and 705 can be formed using an oxide semiconductor material.

In the case where low cost and large size are important, all of the transistors 703, 704, and 705 can be formed using amorphous silicon or microcrystalline silicon.

By providing the photo sensors adjacent to each other (for example, the photo sensor 700_n and the photo sensor 700_ (n + 1)), reflected light from the same point of the detection target can be detected by the two adjacent photo sensors. . The light reflected before the end of light irradiation is detected by one of the adjacent photosensors, and the light reflected after the end of light irradiation is detected on the other side. The accuracy of detection can be increased.

The detection accuracy is clearly different when imaging is performed every frame (for example, every 120 Hz) and when the first imaging and the second imaging are performed with one irradiation light without a time difference. . When imaging is performed every frame (for example, every 120 Hz), for example, if the hand moves 10 cm from right to left, a displacement of about 8 mm (about half of the finger) occurs. Then, since such a shift does not occur, an image can be taken without distortion. In addition to this, even when the hand moves in the range of 0.1 m / s to 10 m / s, the ball is thrown at a high speed, or the animal moves unintentionally, it is detected. High-accuracy imaging can be performed.

Next, an example of a specific driving method of the imaging device including the photosensor 700_n and the photosensor 700_ (n + 1) will be described with reference to timing charts illustrated in FIGS. By using the driving method, it is possible to measure the distance from the imaging device to the object to be detected by three-dimensional imaging using the TOF method. Even if the object to be detected is a moving body and the moving speed is high, the position detection accuracy is not significantly reduced.

FIG. 7 illustrates an example of operations of the photosensor 700_n and the photosensor 700_ (n + 1). FIG. 8 illustrates an example of a distance measurement method by three-dimensional imaging using the characteristics of the driving method and the TOF method.

7 illustrates a timing chart of the signal line 11_n, the signal line 12_n, the signal line 13_n, the node 14_n, and the signal line 16_n in the photosensor 700_n, and the signal line 11_ (n + 1) and the signal line 12_ (n + 1) in the photosensor 700_ (n + 1). ), Signal line 13_ (n + 1), node 14_ (n + 1), and signal line 16_ (n + 1). Three-dimensional imaging is performed between time T1 and time T10.

7 and 8, in the pulse 601 and the pulse 602, “irradiation” is represented by “H”, “non-irradiation” is represented by “L”, and other pulses have high potential. The state is represented by “H”, and the low potential state is represented by “L”.

In the three-dimensional imaging according to one embodiment of the disclosed invention, the object to be detected is irradiated with light once from the light source. In light irradiation, the distance between the light source and the object to be detected may be changed. That is, the detected object may be a moving body, and the moving body may move at a high speed.

The time from time T2 to time T3 is the time until the light irradiated from the light source (irradiated light) arrives at the detected object and the light reflected by the detected object (reflected light) arrives at the imaging device. Represents.

At time T1, the signal line 11_n is set to “H”. Further, the signal line 12 — n is set to “H” (first reset). At this time, the photodiode 702 — n and the transistor 703 — n are turned on, and the node 14 — n is set to “H”.

At time T2, irradiation of light from the light source to the object to be detected is started. In the pulse 601, “L” (non-irradiation) changes to “H” (irradiation). Let this time be irradiation start time. Further, the signal line 11_n is set to “L”, and the signal line 12_n is maintained at “H” (first imaging starts). Note that the first imaging start time coincides with the irradiation start time.

At time T3, the irradiation light emitted from the light source is reflected by the detection object, and the reflected light begins to enter the imaging device. In the pulse 602, “L” (non-irradiation) changes to “H” (irradiation). This time is set as the reflection start time. Time T3 is also the first reflected light detection start time. Detection of reflected light can be started at time T3. The potential of the node 14 — n starts to drop from “H”.

At time T4, the signal line 12_n is kept “H”. The potential of the node 14_n continues to decrease further. At time T4, the signal line 11_ (n + 1) is set to “H”, and the signal line 12_ (n + 1) is set to “H” (second reset). At this time, the photodiode 702_ (n + 1) and the transistor 703_ (n + 1) are turned on, and the node 14_ (n + 1) becomes “H”.

At time T5, the irradiation of light from the light source to the detected object is terminated. In the pulse 601, “H” (irradiation) changes to “L” (non-irradiation). This time is defined as the irradiation end time. Further, the signal line 12 — n is set to “L”. At this time, the first imaging is finished. Note that this first imaging end time coincides with the irradiation end time. Time T5 is also the first reflected light detection end time.

Note that when the signal line 12_n is set to “L”, the potential of the node 14_n changes due to parasitic capacitance between the signal line 12_n and the node 14_n. When the potential change is large, the photocurrent generated by the photodiode 702 — n cannot be accurately acquired in the first imaging and the second imaging. Therefore, in order to reduce the influence of parasitic capacitance, countermeasures such as reducing the capacitance between the gate electrode and the source electrode of the transistor 703 — n or the capacitance between the gate electrode and the drain electrode of the transistor 703 — n and connecting a storage capacitor to the node 14 — n are taken. It is valid. In the photosensor 700 — n according to one embodiment of the present invention, these measures are taken so that a potential change of the node 14 — n due to parasitic capacitance can be ignored.

Note that similar measures are taken for the photosensor 700_ (n + 1) according to one embodiment of the present invention.

In this manner, the potentials of the signal line 11_n and the signal line 12_n are controlled so that the first imaging is started simultaneously with the start of irradiation and the first imaging is ended simultaneously with the end of irradiation.

Between time T3 and time T5 (first reflected light detection period), the potential of the node 14_n changes in accordance with the intensity of reflected light that enters the photodiode 702_n. Due to the off-state current of the photodiode 702 — n, the potential of the node 14 — n starts to be lower than “H”. The off-state current is proportional to the intensity of reflected light with which the photodiode 702 — n is irradiated and the irradiation time.

Here, the relationship between the potential change of the node 14, the intensity of light (reflected light) irradiated to the photodiode 702, and the irradiation time will be described. In the same detection period, the greater the reflected light intensity, the greater the potential change at the node 14. For the same intensity, the longer the reflected light detection period, the greater the potential change at the node 14. Therefore, the greater the reflected light intensity and the longer the reflected light detection period, the greater the off-state current of the photodiode 702 and the greater the potential change at the node 14.

Note that the potential of the node 14_n is constant after the time T5. The potential (V1) of the node 14_n at the time T5 depends on the photocurrent generated by the photodiode 702_n during the first reflected light detection. That is, it is determined according to the reflected light intensity or the like.

Further, the first detection signal is determined in accordance with the potential (V1) of the node 14_n at the time T5. As the first reflected light detection period is longer, the potential change of the node 14_n is larger, so the potential (V1) of the node 14_n at the time T5 is smaller.

The light irradiated to the photodiode 702 — n between time T1 and time T5 is all reflected light. That is, it refers to the light that is irradiated from the light source to the detected object and reflected from the detected object.

In addition, light irradiated on the photodiode 702_ (n + 1) between time T4 and time T7 also indicates reflected light. That is, it refers to the light that is irradiated from the light source to the detected object and reflected from the detected object.

Further, at time T5, the signal line 11_ (n + 1) is set to “L”, and the signal line 12_ (n + 1) is maintained at “H” (second imaging starts). Note that the second imaging start time coincides with the irradiation end time. Time T5 is also the second reflected light detection start time. Detection of reflected light can be started at time T5.

Between time T5 and time T6 (second reflected light detection period), the potential of the node 14_ (n + 1) depends on the intensity of reflected light that enters the photodiode 702_ (n + 1) during the second reflected light detection period. Will change. Due to the off-state current of the photodiode 702_ (n + 1), the potential of the node 14_ (n + 1) starts to be lower than “H”. The off-state current is proportional to the intensity and time of reflected light with which the photodiode 702_ (n + 1) is irradiated. Therefore, the potential of the node 14_ (n + 1) also changes depending on the reflected light intensity and the reflected light detection period.

In the present embodiment, as an example, the second reflected light detection period (time T5 to time T6) is shorter than the first reflected light detection period (time T3 to time T5). Yes. For this reason, the potential change of the node 14 during the second imaging is smaller than the potential change of the node 14 during the first imaging.

At time T6, the reflected light reflected by the object to be detected is incident on the imaging device. The pulse 602 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the reflection end time. Time T6 is also the second reflected light detection end time. On the other hand, the signal line 12_ (n + 1) is maintained at “H”.

Note that the potential of the node 14_ (n + 1) is constant after the time T6. The potential (V2) of the node 14_ (n + 1) at the time T6 depends on the photocurrent generated by the photodiode 702_ (n + 1) during the second reflected light detection. That is, it is determined according to the reflected light intensity or the like.

Further, the second detection signal is determined in accordance with the potential (V2) of the node 14_ (n + 1) at the time T6. The shorter the second reflected light detection period, the smaller the potential change of the node 14_ (n + 1), and thus the potential (V2) of the node 14_ (n + 1) at time T6 increases.

At time T7, the signal line 12_ (n + 1) is set to “L”. At this time, the second imaging is finished.

In this way, the second imaging is started simultaneously with the end of the irradiation, and the second imaging is finished after the imaging at the same time as the first imaging, so that the signal line 11_ (n + 1) and the signal line 12_ (n + 1) are completed. To control the potential.

At time T8, the signal line 13_n is set to “H” (first reading starts). At this time, the transistor 705_n is turned on. In addition, the signal line 15 and the signal line 16_n are turned on through the transistor 704_n and the transistor 705_n. Then, the potential of the signal line 16 — n decreases. Note that before the time T8, the signal line 16_n is subjected to a precharge operation in advance and is set to “H”.

There is no particular limitation on the structure of the reading circuit for performing the precharge operation on the signal line 16 — n. The readout circuit can also be constituted by one Pch transistor 406 as in the readout circuit 401 shown in FIG.

At time T9, the signal line 13_n is set to “L” (end of the first reading). Then, the transistor 705_n is cut off and the potential of the signal line 16_n becomes constant. The potential (V _S1 ) of the signal line 16_n at time T9 depends on the rate of change in potential of the signal line 16_n from time T8 to time T9.

Note that the rate of change in potential of the signal line 16 — n depends on the current between the source electrode and the drain electrode of the transistor 704 — n. That is, it depends on the intensity and irradiation time of light (reflected light) irradiated to the photodiode 702 — n in the first imaging. For the same irradiation time, the higher the reflected light intensity, the slower the potential change rate of the signal line 16_n. For the same intensity, the longer the reflected light detection period, the slower the potential change rate of the signal line 16_n. The slower the potential change rate of the signal line 16_n, the higher the potential (V _S1 ) of the signal line 16_n at the time T9.

Therefore, by acquiring the potential (V _S1 ) of the signal line 16_n at the time T9 by the first reflected light detection, the amount of light (reflected light) incident on the photodiode 702_n during the first imaging period (incided) The detection signal S1 can be obtained by detecting the time product of light intensity. Here, when the intensity of irradiated light is constant and only the first reflected light is incident on the photodiode 702_n, the potential (V _S1 ) of the signal line 16_n is approximately proportional to the first reflected light detection period. To do.

A relationship between the potential of the node 14 and the potential of the signal line 16 will be described. When the intensity of light (reflected light) applied to the photodiode 702 is large, the potential change of the node 14 within a certain period increases. At this time, since the channel resistance of the transistor 704 is increased, the speed of the potential change of the signal line 16 is decreased. Therefore, the potential change of the signal line 16 within a certain period becomes small.

Further, at time T9, the signal line 13_ (n + 1) is set to “H” (second read start). At this time, the transistor 705_ (n + 1) is turned on. In addition, the signal line 15 and the signal line 16_ (n + 1) are brought into conduction through the transistor 704_ (n + 1) and the transistor 705_ (n + 1). Then, the potential of the signal line 16_ (n + 1) decreases. Prior to time T9, the signal line 16_ (n + 1) is precharged in advance and set to “H”.

At time T10, the signal line 13_ (n + 1) is set to “L” (end of second reading). Then, the transistor 705_ (n + 1) is cut off, and the potential of the signal line 16_ (n + 1) becomes constant. The potential (V _S2 ) of the signal line 16_ (n + 1) at time T10 depends on the speed of change in potential of the signal line 16_ (n + 1) from time T9 to time T10.

If the light intensity is the same, the shorter the reflected light detection period, the faster the potential change speed of the signal line 16_ (n + 1). The faster the potential change rate of the signal line 16_ (n + 1), the smaller the potential (V _S2 ) of the signal line 16_ (n + 1) at time T10.

Therefore, by acquiring the potential (V _S2 ) of the signal line 16_ (n + 1) at time T10 by detecting the second reflected light, the light (reflected light) incident on the photodiode 702_ (n + 1) in the second imaging period. ) (The time product of the intensity of the incident light) can be detected to obtain the detection signal S2. Here, when the intensity of irradiated light is constant and only the second reflected light is incident on the photodiode 702_ (n + 1), the potential (V _S2 ) of the signal line 16_ (n + 1) is the second reflection. It is roughly proportional to the light detection period.

In the present embodiment, since the second reflected light detection period (time T5 to time T6) is shorter than the first reflected light detection period (time T3 to time T5), the signal line at time T10. The potential (V _S2 ) of 16_ (n + 1) is smaller than the potential (V _S1 ) of the signal line 16_n at time T9.

At time T10, since the detection signal S1 can be obtained by the first imaging and the detection signal S2 can be obtained by the second imaging, three-dimensional imaging using the TOF method becomes possible.

In addition, as described above, the first reflected light detection period is a period for detecting reflected light from the detection object at the time of irradiation, and the second reflected light detection period is a detection target after the end of irradiation. This is a period during which reflected light from an object is detected. That is, the reflected light from the same point of the object to be detected can be continuously detected by using the adjacent photo sensor.

FIG. 8 illustrates pulses 601 and 602, a pulse of the signal line 12_n, and a pulse of the signal line 12_ (n + 1) in the photosensor 700_n and the photosensor 700_ (n + 1). First, the characteristics of the driving method will be described with reference to FIG. The detection of the reflected light is separated into two times, a first reflected light detection period and a second reflected light detection period. Using the adjacent photo sensor 700_n and photo sensor 700_ (n + 1), the signal line 11_n, the signal line 12_n, and the signal line 11_ (n + 1) are performed so that the first imaging and the second imaging are continuously performed. The main feature of the driving method in one embodiment of the disclosed invention is that the potential of the signal line 12_ (n + 1) is controlled to devise the timing of imaging time.

While comparing the pulses shown in FIG. 8, description will be made separately for each period such as an irradiation period, a reflection period, an imaging period, and a reflected light detection period.

As shown in the pulse 601, time T2 is the irradiation start time, time T5 is the irradiation end time, and time T2 to time T5 are the irradiation period. As shown by a pulse 602, time T3 is a reflection start time, time T6 is a reflection end time, and time T3 to time T6 are reflection periods. The reflection period is equal to the irradiation period.

As shown by the pulse (TX_n) of the signal line 12_n, time T2 is the first imaging start time, time T5 is the first imaging end time, and time T2 to time T5 are the first imaging period. Time T3 is the first reflected light detection start time, time T5 is the first reflected light detection end time, and times T3 to T5 are the first reflected light detection period.

The first imaging must be started at least before the reflection period. Further, the first imaging must be completed simultaneously with the end of the irradiation period. In this manner, the potentials of the signal line 11_n and the signal line 12_n are controlled so that the timing of the imaging period is determined.

Further, as shown in the pulse (TX_ (n + 1)) of the signal line 12_ (n + 1), the time T5 is the second imaging start time, the time T7 is the second imaging end time, and the times T5 to T7 are This is the second imaging period. Time T5 is the second reflected light detection start time, time T6 is the second reflected light detection end time, and time T5 to time T6 are the second reflected light detection period.

The second imaging must be started simultaneously with the end of the irradiation period. Further, the second imaging must be completed at least after the reflection period. In this manner, the potentials of the signal line 11_ (n + 1) and the signal line 12_ (n + 1) are controlled so that the timing of the imaging period is determined.

That is, the detection period of the reflected light irradiated to the photosensor 700_n and the photosensor 700_ (n + 1) in the reflection period is separated into two times, and the first reflected light in the first imaging period is separated by the photosensor 700_n. By detecting and detecting the second reflected light within the second imaging period by the photo sensor 700_ (n + 1), it becomes possible to perform imaging continuously in time.

Note that the first reflected light detection period is performed within the first imaging period. Further, the second reflected light detection period is performed within the second imaging period. Then, the first detection signal S1 that depends on the delay time of the light acquired from the first reflected light detection is acquired, and the second detection signal S2 that depends on the delay time of the light acquired from the second reflected light detection. By acquiring, the distance from the imaging device to the detected object can be measured.

Next, an example of a distance measurement method using three-dimensional imaging using the TOF method will be described. An example of a method for measuring the distance from the imaging device to the detection object using the first detection signal S1 and the second detection signal S2 will be described using a calculation formula.

Here, the intensity of irradiation light from the light source to the object to be detected is constant, and in the first imaging period and the second imaging period, the first reflected light and the photodiode 702_n and the photodiode 702_ (n + 1) respectively Assuming that only the second reflected light is incident, the potential (V _S1 ) of the signal line 16 — n is approximately proportional to the first reflected light detection period, and the potential (V _S2 ) of the signal line 16 — (n + 1) is the second Is substantially proportional to the reflected light detection period.

That is, the first detection signal S1 obtained by the first imaging generally depends on the first reflected light detection period, and the second detection signal S2 obtained by the second imaging is the second reflected light detection. It largely depends on the period.

The first detection signal S1 and the second detection signal S2 can be expressed by equations (2) and (3), respectively, using a proportional constant α, an irradiation period T, and a delay time Δt.

When the proportionality constant α is eliminated from the equations (2) and (3), the delay time Δt is obtained as shown in the equation (4).

Furthermore, using the above-described equation (x = (c × Δt) / 2) for the distance x from the light source to the object to be detected and Equation (4), the distance x from the imaging device to the object to be detected It can be represented by (1).

Thus, if the first detection signal S1 and the second detection signal S2 are obtained, the distance x from the imaging device to the detected object can be obtained.

Alternatively, the third imaging may be performed by the photosensor 700_n or the photosensor 700_ (n + 1) in a period in which light irradiation from the light source is not performed. In this case, the third detection signal S3 is obtained by the third imaging. The third detection signal S3 is subtracted from the first detection signal S1, and further, the third detection signal S3 is subtracted from the second detection signal S2, and the detection signal S1 and the detection signal S2 in the above formula (1) are renewed. By doing so, the influence of natural light can be removed.

As a result, a photosensor is configured with a small number of elements, and by devising a driving method in an imaging apparatus equipped with the photosensor, three-dimensional imaging using the TOF method can be realized, and the function as a distance measuring apparatus is achieved. You can see that Therefore, it is possible to solve the problem that the number of elements of the photosensor generated when the TOF method is applied, and to realize an imaging device advantageous for pixel miniaturization.

In addition, the light reflected from the light source before the end of irradiation on the detected object is detected by one of the adjacent photosensors, and the light reflected after the end of irradiation is detected on the other side, so that the detected object can be moved at high speed. Even if it moves, it becomes possible to measure the distance from the light source to the detected object (moving body) without reducing the position detection accuracy.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 4)
In this embodiment, an example of a driving method of an imaging device capable of performing two-dimensional imaging and three-dimensional imaging using the TOF method at once will be described with reference to FIGS. Note that the photosensor included in the imaging device has a structure in which a first photosensor that absorbs visible light and a second photosensor that absorbs infrared light overlap.

In the three-dimensional imaging, the first imaging and the second imaging are performed in correspondence with the first infrared light irradiation and the second infrared light irradiation (the timing is different with the same length), and the first imaging is performed. From the first infrared reflected light detection for detecting the first reflected light by the infrared light irradiation, a first detection signal depending on the delay time of the light is acquired, and the second detection by the second infrared light irradiation is performed. The distance from the light source to the object to be detected is measured by acquiring a second detection signal depending on the light delay time from the second infrared reflected light detection for detecting the reflected light. In the two-dimensional imaging, the third imaging is performed and the third detection signal is acquired, thereby acquiring the brightness, color, and the like of the detected object.

A structure of a photosensor included in an imaging device of one embodiment of the invention disclosed in this specification will be described with reference to FIGS. The photo sensor 800 includes a first photo sensor 800A and a second photo sensor 800B.

As shown in FIG. 9, an example in which the first photosensor 800A and the second photosensor 800B have the same configuration will be described. The first photosensor 800A includes three transistors and one photodiode. In addition, the second photosensor 800B includes three transistors and one photodiode. As shown in FIG. 9A, the first photosensor 800A includes a first photodiode 802A, a first transistor 804A, a second transistor 805A, and a third transistor 803A. Similarly, as illustrated in FIG. 9B, the second photosensor 800B includes a second photodiode 802B, a first transistor 804B, a second transistor 805B, and a third transistor 803B.

FIG. 10A is an example of a circuit diagram illustrating a structure of a photosensor 800 included in the imaging device. As shown in FIG. 10A, the first photosensor 800A and the second photosensor 800B are adjacent to each other. Specifically, as illustrated in FIG. 10B, the first photodiode 802A and the second photodiode 802B overlap with each other, and the first photodiode 802A is in contact with the second photodiode 802B. The light (including visible light and infrared light) applied to the photosensor 800 is disposed at a position where the light is incident first.

Note that light irradiated on the photosensor 800 in this specification is reflected light. In this specification, the light irradiating the first photodiode 802A means light that is reflected from the object to be detected when one or both of light from the light source and natural light are irradiated to the object to be detected. Yes (visible light). Further, the light applied to the second photodiode 802B means light that is irradiated from the light source to the object to be detected and reflected from the object to be detected (infrared light).

By providing the first photosensor 800A and the second photosensor 800B in an overlapping manner, the area can be shared when arranging each sensor, so that the area occupied by the photosensor in the imaging device can be reduced. Can do. Accordingly, the pixel can be miniaturized.

In addition, the semiconductor layer of the first photodiode 802A has a characteristic of mainly absorbing visible light and transmitting most of infrared light. For example, amorphous silicon or the like can be used for the semiconductor layer of the first photodiode 802A.

In addition, the semiconductor layer of the second photodiode 802B has a characteristic of absorbing infrared light. For example, polycrystalline silicon, microcrystalline silicon, single crystal silicon, or the like can be used for the semiconductor layer of the second photodiode 802B.

Therefore, visible light incident on the second photodiode 802B can be reduced by first absorbing visible light with respect to the second photodiode 802B with the first photodiode 802A.

That is, the first photosensor 800A uses visible light, and the second photosensor 800B uses infrared light.

9A and 10A, the signal line 11A is a reset signal line (PR_2). The signal line 12A is a charge storage signal line (TX_2). The signal line 13A is a selection signal line (SE_2). The node 14A is a floating diffusion (FD) node (FD_2). The signal line 16A is a photosensor output signal line. In FIG. 9B and FIG. 10A, the signal line 11B is a reset signal line (PR_3). The signal line 12B is a charge accumulation signal line (TX_3). The signal line 13B is a selection signal line (SE_3). The node 14B is a floating diffusion (FD) node (FD_3). The signal line 16B is a photosensor output signal line. The signal line 15 is a photosensor reference signal line, and can be shared by the first photosensor 800A and the second photosensor 800B.

As shown in FIG. 10A, in the photosensor 800, the anode of the photodiode 802 is electrically connected to the signal line 11, and the cathode of the photodiode 802 is one of the source electrode and the drain electrode of the third transistor 803. And are electrically connected. The other of the source electrode and the drain electrode of the third transistor 803, the gate electrode of the first transistor 804, and the node 14 are electrically connected. One of the source electrode and the drain electrode of the first transistor 804 and the signal line 15 are electrically connected. One of the source electrode and the drain electrode of the second transistor 805 and the signal line 16 are electrically connected. The other of the source electrode and the drain electrode of the first transistor 804 and the other of the source electrode and the drain electrode of the second transistor 805 are electrically connected. The gate electrode of the third transistor 803 and the signal line 12 are electrically connected, and the gate electrode of the second transistor 805 and the signal line 13 are electrically connected.

9A and 9B, the anode of the photodiode 802 is electrically connected to the signal line 11, and the cathode of the photodiode 802 is electrically connected to one of the source electrode and the drain electrode of the third transistor 803. However, the present invention is not limited to this. The cathode of the photodiode 802 may be electrically connected to the signal line 11, and the anode of the photodiode 802 may be electrically connected to one of the source electrode and the drain electrode of the third transistor 803.

The photodiode 802 is a photoelectric conversion element that generates current when irradiated with light. Therefore, a photocurrent flows through the photodiode 802 by detecting the light reflected from the object to be detected.

The third transistor 803 functions as a transistor that controls imaging time. In one embodiment of the disclosed invention, the potential of the signal line 11 is switched from “L (Low)” to “H (High)”, and the potential of the gate electrode of the third transistor 803 (the potential of the signal line 12) is When switching from “L” to “H”, positive charges are accumulated in the node 14. When the potential of the signal line 11 is switched from “H” to “L” while the potential of the gate electrode of the third transistor 803 (the potential of the signal line 12) is maintained at “H”, imaging starts, and the photodiode Negative charges are accumulated in the node 14 in accordance with the light radiated to 802. In this manner, the third transistor 803 can change the amount of charge accumulated in the node 14 by setting the potential of the gate electrode to “H” or “L”. The end of imaging is when the potential of the gate electrode of the third transistor 803 (the potential of the signal line 12) is switched from “H” to “L”.

In the three-dimensional imaging, the potentials of the signal line 11B (PR_3) and the signal line 12B (TX_3) are controlled. Specifically, in the first imaging, the first imaging starts at the same time as the first irradiation starts, and the first imaging ends at the same time as the first irradiation ends. Control the potential. In the second imaging, the second imaging starts at the same time as the second irradiation ends, and the second imaging ends after the imaging at the same time as the first imaging. Control the potential.

In the two-dimensional imaging, the potentials of the signal line 11A (PR_2) and the signal line 12A (TX_2) are controlled. Specifically, in the third imaging, the potentials of the signal line 11A and the signal line 12A are set so that the third imaging starts at the same time as the first imaging starts and the third imaging ends after the second imaging ends. To control.

The first transistor 804 functions as a transistor that amplifies the charge accumulated in the node 14. The second transistor 805 functions as a transistor that controls the output of the photosensor. When the signal (the potential of the signal line 13) input to the gate electrode of the second transistor 805 is switched from “L” to “H”, the signal is read.

The third transistor 803, the first transistor 804, and the second transistor 805 have functions similar to those of the transistor 403, the transistor 404, and the transistor 405 described in the above embodiment, respectively. Therefore, the above embodiment can be referred to for a semiconductor layer which is preferably used.

A method for driving the imaging device including the photosensor 800 will be described. By using the driving method, two-dimensional imaging and three-dimensional imaging using the TOF method can be performed at a time. In addition, since the first photosensor 800A and the second photosensor 800B are superimposed, two-dimensional imaging using the first photosensor 800A that absorbs visible light while achieving pixel miniaturization; Three-dimensional imaging using the second photosensor 800B that absorbs infrared light can be performed.

A specific driving method will be described with reference to timing charts shown in FIGS. First, the operation of the photosensor 800 will be described with reference to FIG. In FIG. 12, the characteristics of the driving method and a method for performing two-dimensional imaging and three-dimensional imaging using the TOF method at once will be described.

FIG. 11 is a timing chart of the photosensor 800. Two-dimensional imaging and three-dimensional imaging are performed between time T1 and time T18.

11 and 12, in the pulse 901 and the pulse 902, “irradiation” is represented by “H”, “non-irradiation” is represented by “L”, and other pulses have a high potential. The state is represented by “H”, and the low potential state is represented by “L”.

In the three-dimensional imaging, irradiation (first irradiation and second irradiation) is performed twice from the light source to the detected object. Note that the second irradiation is different in timing from the first irradiation and is performed for the same time. In the first irradiation and the second irradiation, the distance between the light source and the object to be detected is not changed, and the time from time T2 to time T3 (delay time) and the time from time T8 to time T9 (delay) It is obvious that time is equal.

At time T1, the signal line 11B is set to “H”. Further, the signal line 12B is set to “H” (first reset in three-dimensional imaging). At this time, the second photodiode 802B and the third transistor 803B are turned on, and the node 14B becomes “H”.

Similarly, the signal line 11A is set to “H”. Further, the signal line 12A is set to “H” (first reset in two-dimensional imaging). At this time, the first photodiode 802A and the third transistor 803A are turned on, and the node 14A becomes “H”.

At time T2, irradiation of the first light from the light source to the object to be detected is started. In the pulse 901, “L” (non-irradiation) changes to “H” (irradiation). Let this time be the first irradiation start time. Further, the signal line 11B is set to “L” and the signal line 12B is maintained at “H” (first imaging starts). Note that the first imaging start time coincides with the first irradiation start time.

Similarly, the signal line 11A is set to “L”, and the signal line 12A is maintained at “H” (start of the third imaging). According to this configuration, since the first photodiode 802A that absorbs visible light and the second photodiode 802B that absorbs infrared light are configured to overlap, the first imaging and the third imaging are performed. Can be started simultaneously.

At time T3, the first irradiation light emitted from the light source is reflected by the object to be detected, and the first reflected light (infrared light) starts to enter the imaging apparatus. In the pulse 902, “L” (non-irradiation) changes to “H” (irradiation). Let this time be the first reflection start time. Time T3 is also the first reflected light detection start time. Detection of reflected light can be started at time T3. Further, the signal line 12A is maintained at “H”.

During time T3 to time T4 (first reflected light detection period), the potential of the node 14B changes according to the intensity of the first reflected light. Due to the off-state current of the second photodiode 802B, the potential of the node 14B starts to be lower than “H”. The off-current is proportional to the intensity of the reflected light and the irradiation time applied to the second photodiode 802B.

Similarly, the potential of the node 14A starts to drop from “H”.

Here, the relationship between the potential change of the node 14 and the intensity and irradiation time of the reflected light applied to the photodiode 802 will be described. In the same detection period, the greater the reflected light intensity, the greater the potential change at the node 14. For the same intensity, the longer the reflected light detection period, the greater the potential change at the node 14. Therefore, as the reflected light intensity increases and the reflected light detection period increases, the off-state current of the photodiode 802 increases and the potential change at the node 14 also increases.

At time T4, the irradiation of the first light from the light source to the detected object is terminated. The pulse 901 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the first irradiation end time. Further, the signal line 12B is set to “L”. At this time, the first imaging is finished. Note that the first imaging end time coincides with the first irradiation end time. Time T4 is also the first reflected light detection end time. On the other hand, the signal line 12A is maintained at “H”.

As described above, the potentials of the signal line 11B and the signal line 12B are controlled so that the first imaging is started simultaneously with the start of the first irradiation and the first imaging is ended simultaneously with the end of the first irradiation.

Note that the potential of the node 14B is constant after the time T4. The potential (V1) of the node 14B at time T4 depends on the photocurrent generated by the photodiode 802 during the first reflected light detection. That is, it is determined according to the reflected light intensity or the like. On the other hand, the potential of the node 14A continues to decrease.

Further, the first detection signal is determined in accordance with the potential (V1) of the node 14B at the time T4. As the first reflected light detection period is longer, the potential change of the node 14B is larger, so the potential (V1) of the node 14B at the time T4 is smaller.

The light irradiated to the second photodiode 802B between the time T1 and the time T4 is assumed to indicate all reflected light by the first reflection. That is, it refers to the light that is irradiated from the light source to the detected object and reflected from the detected object. The reflected light is infrared light.

In addition, all the light applied to the first photodiode 802A between the time T1 and the time T16 also indicates reflected light. That is, it is assumed that one or both of light from the light source and natural light is irradiated on the object to be detected and reflected from the object to be detected. The reflected light is visible light.

At time T5, the incident of the reflected light by the first reflection reflected by the detection object to the imaging device is completed. The pulse 902 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the first reflection end time. On the other hand, the signal line 12A is maintained at “H”.

Note that when the signal line 12B is set to “L”, the potential of the node 14B changes due to the parasitic capacitance between the signal line 12B and the node 14B. When the potential change is large, the generated photocurrent cannot be accurately acquired by the second photodiode 802B in the first imaging and the second imaging. Therefore, in order to reduce the influence of the parasitic capacitance, a storage capacitor is connected to the node 14B, which reduces the capacitance between the gate electrode and the source electrode of the third transistor 803B or the capacitance between the gate electrode and the drain electrode of the third transistor 803B. It is effective to take measures such as In the second photosensor 800B according to one embodiment of the present invention, these countermeasures are taken so that the potential change of the node 14B due to the parasitic capacitance can be ignored.

Note that the same measures are taken for the first photosensor 800A according to one embodiment of the present invention.

At time T6, the signal line 13B is set to “H” (first reading start). At this time, the second transistor 805B is turned on. In addition, the signal line 15 and the signal line 16B are brought into conduction through the first transistor 804B and the second transistor 805B. Then, the potential of the signal line 16B decreases. Prior to time T6, the signal line 16B is pre-charged in advance and set to “H”.

The configuration of the readout circuit that performs the precharge operation on the signal line 16 is not particularly limited. The readout circuit can also be constituted by one Pch transistor 406 as in the readout circuit 401 shown in FIG.

At time T7, the signal line 13B is set to “L” (end of the first reading). Then, the second transistor 805B is cut off, and the potential of the signal line 16B becomes constant. The potential (V _S1 ) of the signal line 16B at time T7 depends on the speed of change in potential of the signal line 16B from time T6 to time T7.

The speed of the potential change of the signal line 16 depends on the current between the source electrode and the drain electrode of the first transistor 804. That is, in the first imaging, it depends on the intensity and irradiation time of the reflected light (infrared light) irradiated to the second photodiode 802B from time T3 to time T4. In the second imaging, it depends on the intensity of the reflected light (infrared light) irradiated to the second photodiode 802B at time T11 to time T12 and the irradiation time. In the third imaging, it depends on the intensity and irradiation time of the reflected light (visible light) irradiated to the first photodiode 802A from time T3 to time T16.

For the same irradiation time, the higher the reflected light intensity, the slower the potential change speed of the signal line 16B. If the light intensity is the same, the longer the reflected light detection period, the slower the potential change speed of the signal line 16B. The slower the potential change speed of the signal line 16B, the higher the potential (V _S1 , V _S2 ) of the signal line 16B.

For the same irradiation time, the higher the reflected light intensity, the slower the potential change speed of the signal line 16A. If the light intensity is the same, the longer the reflected light detection period, the slower the potential change speed of the signal line 16A. The slower the potential change rate of the signal line 16A, the higher the potential (V _S3 ) of the signal line 16A.

A relationship between the potential of the node 14 and the potential of the signal line 16 will be described. When the intensity of light applied to the photodiode 802 is high, the potential change of the node 14 within a certain period increases, so the value of the potential of the node 14 decreases. At this time, since the channel resistance of the first transistor 804 is increased, the speed of the potential change of the signal line 16 is decreased. Accordingly, since the potential change of the signal line 16 within a certain period becomes small, the potential value of the signal line 16 becomes high.

By acquiring the potential (V _S1 ) of the signal line 16B at the time T7 by the first reflected light detection, the amount of reflected light irradiated to the second photodiode 802B during the first imaging period (incident light Detection signal S1 can be obtained. Here, assuming that the intensity of light in the first irradiation is constant and only the reflected light by the first reflection is irradiated, the potential (V _S1 ) of the signal line 16B is approximately proportional to the first reflected light detection period. .

At time T8, irradiation of the second light from the light source to the object to be detected is started. The pulse 901 changes from “L” (non-irradiation) to “H” (irradiation). This time is set as the second irradiation start time. Further, the signal line 12A is maintained at “H”.

At time T9, the second irradiation light emitted from the light source is reflected by the detection object, and the second reflected light starts to enter the imaging apparatus. The pulse 902 changes from “L” (non-irradiation) to “H” (irradiation). This time is set as the second reflection start time.

At time T10, the signal line 11B is set to “H”, and the signal line 12B is set to “H” (second reset in three-dimensional imaging). At this time, the second photodiode 802B and the third transistor 803B are turned on, and the node 14B becomes “H”.

At time T11, the irradiation of the second light from the light source to the detected object is terminated. The pulse 901 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the second irradiation end time. The signal line 11B is set to “L”, and the signal line 12B is kept “H” (second imaging starts). Note that the second imaging start time coincides with the second irradiation end time. The time T11 is also the second reflected light detection start time. Detection of reflected light can be started at time T11. Further, the signal line 12A is maintained at “H”.

During time T11 to time T12 (second reflected light detection period), the potential of the node 14B changes according to the intensity of the second reflected light. Due to the off-state current of the second photodiode 802B, the potential of the node 14B starts to be lower than “H”. The off-current is proportional to the intensity of the reflected light and the irradiation time applied to the second photodiode 802B. Therefore, the potential of the node 14B also changes depending on the reflected light intensity and the reflected light detection period.

In the present embodiment, as an example, the second reflected light detection period (time T11 to time T12) is shorter than the first reflected light detection period (time T3 to time T4). Yes. For this reason, the potential change of the node 14 during the second imaging is smaller than the potential change of the node 14 during the first imaging.

At time T12, the incident of the reflected light by the second reflection reflected by the object to be detected on the imaging device is completed. The pulse 902 changes from “H” (irradiation) to “L” (non-irradiation). This time is set as the second reflection end time. The time T12 is also the second reflected light detection end time. On the other hand, the signal line 12A is maintained at “H”.

Note that the potential of the node 14B is constant after the time T12. The potential (V2) of the node 14B at the time T12 depends on the photocurrent generated by the second photodiode 802B during the second reflected light detection. That is, it is determined according to the reflected light intensity or the like. On the other hand, the potential of the node 14A continues to decrease.

Further, the second detection signal is determined in accordance with the potential (V2) of the node 14 at the time T12. The shorter the second reflected light detection period, the smaller the potential change of the node 14, and thus the potential (V 2) of the node 14 at time T 12 becomes larger.

At time T13, the signal line 12B is set to “L”. At this time, the second imaging is finished.

In this way, the potentials of the signal line 11B and the signal line 12B are controlled so that the second imaging starts at the same time as the second irradiation ends and the second imaging ends after the first imaging. .

Note that the light applied to the second photodiode 802B between time T10 and time T13 is all reflected light by the second reflection. That is, it refers to light that is irradiated from the light source to the detected object and reflected from the detected object. The reflected light is infrared light.

At time T14, the signal line 13B is set to “H” (second read start). At this time, the second transistor 805B is turned on. In addition, the signal line 15 and the signal line 16B are brought into conduction through the first transistor 804B and the second transistor 805B. Then, the potential of the signal line 16B decreases. Prior to time T14, the signal line 16B is pre-charged in advance and set to “H”.

At time T15, the signal line 13B is set to “L” (end of second reading). Then, the second transistor 805B is cut off, and the potential of the signal line 16B becomes constant. The potential (V _S2 ) of the signal line 16B at time T15 depends on the speed of change in potential of the signal line 16B from time T14 to time T15.

Therefore, by acquiring the potential (V _S2 ) of the signal line 16B at the time T15 by detecting the second reflected light, the amount of incident light (incident on the second photodiode 802B during the second imaging period). Detection signal S2 can be obtained. Here, assuming that the intensity of light in the second irradiation is constant and only the reflected light by the second reflection is irradiated, the potential (V _S2 ) of the signal line 16B is approximately proportional to the second reflected light detection period. .

In the present embodiment, since the second reflected light detection period (time T11 to time T12) is shorter than the first reflected light detection period (time T3 to time T4), the signal line at time T15. The potential (V _S2 ) of 16B is smaller than the potential (V _S1 ) of the signal line 16B at time T7.

At time T15, the detection signal S1 can be obtained by the first imaging, and the detection signal S2 can be obtained by the second imaging. Therefore, three-dimensional imaging using the TOF method can be performed.

At time T16, the signal line 12A is set to “L”. At this time, the third imaging is finished.

At time T17, the signal line 13A is set to “H” (start of third reading). At this time, the second transistor 805A is turned on. In addition, the signal line 15 and the signal line 16A are brought into conduction through the first transistor 804A and the second transistor 805A. Then, the potential of the signal line 16A decreases. Prior to time T17, the signal line 16A is pre-charged in advance and set to “H”.

At time T18, the signal line 13A is set to “L” (end of the third reading). Then, the second transistor 805A is cut off, and the potential of the signal line 16A becomes constant. The potential (V _S3 ) of the signal line 16A at time T18 depends on the speed of change in potential of the signal line 16A from time T3 to time T16.

By acquiring the potential (V _S3 ) of the signal line 16A at time T18 by detecting reflected light (visible light) irradiated to the first photodiode 802A (third reflected light detection), the third imaging is performed. The amount of reflected light (the time product of the intensity of the incident light) irradiated to the first photodiode 802A during the period can be detected, and the detection signal S3 can be obtained. Here, if the intensity of one or both of light from the light source and natural light is constant, the potential (V _S3 ) of the signal line 16A is approximately proportional to the third reflected light detection period.

Since the detection signal S3 can be obtained by the third imaging at the time T18, it is possible to perform the three-dimensional imaging using the TOF method while performing the two-dimensional imaging.

FIG. 12 shows a pulse 901, a pulse 902, a pulse of the signal line 12A, and a pulse of the signal line 12B in the photosensor 800. The features of the driving method will be described with reference to FIG. The potential of the gate electrode of the third transistor 803B is set to “H” in the first reflected light detection period in the first imaging period, and in the second reflected light detection period in the second imaging period. The potential of the gate electrode of the third transistor 803A is set to “H” so that the potential of the gate electrode of the third transistor 803B is “H” and includes the first imaging period and the second imaging period. Control to be H ”. Thus, it is possible to perform 3D imaging during 2D imaging.

While comparing each pulse shown in FIG. 12, description will be made separately for each period such as an irradiation period, a reflection period, an imaging period, and a reflected light detection period.

As shown in the pulse 901, the time T2 is the first irradiation start time, the time T4 is the first irradiation end time, and the times T2 to T4 are the first irradiation period. Time T8 is the second irradiation start time, time T11 is the second irradiation end time, and time T8 to time T11 are the second irradiation period. In one embodiment of the disclosed invention, the first irradiation period and the second irradiation period are necessarily equal.

As shown in the pulse 902, the time T3 is the first reflection start time, the time T5 is the first reflection end time, and the times T3 to T5 are the first reflection period. Time T9 is the second reflection start time, time T12 is the second reflection end time, and time T9 to time T12 are the second reflection period. The reflection period is equal to the irradiation period.

That is, the first irradiation period and the second irradiation period are equal, and the first reflection period and the second reflection period are equal.

As shown in the pulse (TX_3) of the signal line 12B, time T2 is the first imaging start time, time T4 is the first imaging end time, and time T2 to time T4 are the first imaging period. Time T3 is the first reflected light detection start time, time T4 is the first reflected light detection end time, and time T3 to time T4 are the first reflected light detection period.

The first imaging must be started at least before the first reflection period. Further, the first imaging must be completed simultaneously with the end of the first irradiation period. In this manner, the potentials of the signal line 11B and the signal line 12B are controlled so that the timing of the imaging period is determined.

Furthermore, as indicated by the pulse (TX_2) of the signal line 12A, time T11 is the second imaging start time, time T13 is the second imaging end time, and time T11 to time T13 are the second imaging period. is there. Time T11 is the second reflected light detection start time, time T12 is the second reflected light detection end time, and time T11 to time T12 are the second reflected light detection period.

The second imaging must be started simultaneously with the end of the second irradiation period. Also, the second imaging must end at least after the second reflection period. In this manner, the potentials of the signal line 11B and the signal line 12B are controlled so that the timing of the imaging period is determined.

That is, the first imaging period is determined corresponding to the first reflection period, and the second imaging period is determined corresponding to the second reflection period, so that the reflected light detection is separated twice. To do.

Next, as shown in the pulse (TX_2) of the signal line 12A, time T2 is the third imaging start time, time T16 is the third imaging end time, and time T2 to time T16 are the third imaging period. It is. Time T3 is the third reflected light detection start time, time T16 is the third reflected light detection end time, and time T3 to time T16 are the third reflected light detection period.

The third imaging must be started simultaneously with the first imaging period, or at least before the first imaging period. Further, the third imaging must end at the same time as the second imaging period or at least after the second imaging period. Thus, the potentials of the signal line 11A and the signal line 12A are controlled so that the timing of the imaging period is determined.

That is, by determining the third imaging period so as to include the first imaging period and the second imaging period, it is possible to perform three-dimensional imaging during two-dimensional imaging.

Note that in one embodiment of the disclosed invention, the first reflected light detection period is equal to a period in which the first irradiation period and the first reflection period overlap with each other, and is a net first imaging period. Further, the second reflected light detection period is equal to the second reflection period after the second irradiation period, and is a net second imaging period. A first detection signal depending on the light delay time is obtained from the first reflected light detection, and a second detection signal depending on the light delay time is obtained from the second reflected light detection. Thus, the distance from the imaging device to the object to be detected can be measured (three-dimensional imaging).

In addition, the third reflected light detection period includes a first imaging period and a second imaging period. By acquiring the third detection signal from the third reflected light detection, the brightness, color, and the like of the detection object can be acquired (two-dimensional imaging).

Next, a distance measurement method using three-dimensional imaging using the TOF method will be described. Imaging using the first detection signal S1 that depends on the delay time of the light acquired from the first reflected light detection and the second detection signal S2 that depends on the delay time of the light acquired from the second reflected light detection A method for measuring the distance from the apparatus to the object to be detected will be described using a calculation formula.

Here, the intensity of light in the first irradiation and the second irradiation is constant, and the first reflected light and the second light are applied to the second photodiode 802B in the first imaging period and the second imaging period, respectively. As a result, the potential (V _S1 ) of the signal line 16B is approximately proportional to the first reflected light detection period, and the potential (V _S2 ) of the signal line 16B is equal to the second reflected light detection period. Is roughly proportional to

That is, the first detection signal S1 obtained by the first imaging generally depends on the first reflected light detection period, and the second detection signal S2 obtained by the second imaging is the second reflected light detection. It largely depends on the period.

The first detection signal S1 and the second detection signal S2 can be expressed by equations (2) and (3), respectively, using a proportional constant α, an irradiation period T, and a delay time Δt.

When the proportionality constant α is eliminated from the equations (2) and (3), the delay time Δt is obtained as shown in the equation (4).

Furthermore, when using the above-described equation (x = (c × Δt) / 2) for the distance x from the light source to the object to be detected and Equation (4), the distance x from the imaging device to the object to be detected is It can be represented by (1).

Thus, if the first detection signal S1 and the second detection signal S2 are obtained, the distance x from the imaging device to the detected object can be obtained.

Further, the fourth imaging may be performed by the second photosensor 800B during a period in which light irradiation from the light source is not performed. In this case, the fourth detection signal S4 is obtained by the fourth imaging. The fourth detection signal S4 is subtracted from the first detection signal S1, and further, the fourth detection signal S4 is subtracted from the second detection signal S2, and the detection signal S1 and the detection signal in Equation (1) are renewed. By setting to S2, the influence of natural light can be removed.

By configuring a photosensor with a small number of elements and devising a driving method in an imaging device equipped with the photosensor, it is possible to realize 3D imaging using the TOF method during 2D imaging. It turns out that the function as an imaging device which acquires 2D information and 3D information simultaneously can be fulfilled. Therefore, it is possible to solve the problem that the number of elements of the photosensor generated when the TOF method is applied, and to realize an imaging device advantageous for pixel miniaturization.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 5)
In this embodiment, an example in which a motion recognition device having an imaging device to which the TOF method is applied is applied to a mobile phone will be described with reference to FIG.

FIG. 14 is a schematic configuration diagram of a mobile phone 5000 in which an imaging device is mounted on the display unit. By mounting the imaging device on the display unit, it is possible to increase the area of the display unit in the mobile phone 5000 and obtain a more accurate three-dimensional distance image and color image. Note that the imaging device can be mounted in a place other than the display unit of the mobile phone, and the imaging device can be mounted in both the display unit and the display unit of the mobile phone. In any case, according to one embodiment of the disclosed invention, it is possible to acquire a three-dimensional distance image and a color image by irradiating the detection object with light.

In FIG. 14, the display unit of the mobile phone 5000 has a function of acquiring a three-dimensional distance image and a color image of an object to be detected in addition to a function of displaying display information. Accordingly, it is not necessary to provide a separate camera outside the mobile phone 5000, so that a simple configuration can be provided.

As shown in FIG. 14A, a cellular phone 5000 includes a speaker 5001, a housing 5002, a display portion 5003 incorporated in the housing 5002, operation buttons 5004, and the like.

FIG. 14 shows an operation of the cellular phone 5000 by an operator's gesture (for example, hand gesture) as an example. In the recognition range 5005, the operator can operate the mobile phone 5000 by performing a gesture without directly touching the mobile phone 5000. Note that the recognition range 5005 is directly above the display portion 5003.

As shown in FIG. 14B, in the recognition range 5005 of the display portion 5003, for example, when the operator performs an operation of “raises the index finger of the right hand”, the calling number 1 is input to the mobile phone.

As shown in FIG. 14C, in the recognition range 5005 of the display unit 5003, for example, when the operator performs an operation of “raises the index finger and middle finger of the right hand”, the calling number 2 is input to the mobile phone.

As shown in FIG. 14D, in the recognition range 5005 of the display unit 5003, for example, when the operator performs an operation of “raises the index finger, middle finger and ring finger of the right hand”, the calling number 3 is input to the mobile phone. .

An operator can operate the cellular phone without touching the operation button 5004 or the display portion 5003 with a finger or the like. In other words, the operator can perform all operations such as making a call or typing an e-mail with only a gesture.

A specific object pattern is stored in the first storage unit mounted on the mobile phone 5000, and a specific operation pattern is stored in the second storage unit. Specific examples of the specific object pattern include “raise the index finger and middle finger of the right hand”, “raise the index finger and middle finger of the right hand”, and “raise the index finger, middle finger and ring finger of the right hand”. Note that the specific object pattern stored in the first storage unit and the specific operation pattern stored in the second storage unit may be arbitrarily determined by the operator. For example, by storing gestures that are routinely used by the operator such as “waving both hands vertically and horizontally” and “turning both hands to the left and right” as a specific operation pattern, the operator can make the mobile phone 5000 extremely intuitive. It becomes possible to operate.

In the information processing apparatus mounted on the mobile phone 5000, processing that ensures the operation is performed on the mobile phone based on the specific operation pattern described above.

Note that the display portion 5003 may have a light-transmitting property.

The cellular phone 5000 does not choose the state of the operator's hand. Even if the hand of the operator who performs the hand gesture is dirty or the operator who performs the hand gesture wears gloves, there is no problem in the operation of the mobile phone 5000. In the recognition range 5005, the operator can easily operate the cellular phone 5000 in a non-contact manner by performing a hand gesture. Furthermore, it is not necessary to be a hand accurately, and gestures can be recognized without problems even if a stick is used instead of a hand.

Note that the mobile phone 5000 can also recognize color image information. Therefore, for example, the operation can be changed depending on the color of the glove.

Even when the operator's hand moves at high speed, the mobile phone 5000 can capture a three-dimensional distance image without distortion, and can easily acquire position change information and shape change information.

Further, even if the operator has some trouble, the cellular phone 5000 can be normally operated. For example, the cellular phone 5000 can be operated using a prosthetic finger, a prosthetic limb (prosthetic hand / prosthetic leg), and the like.

Further, when the operator does not have the ability to recognize the display information displayed on the display unit 5003, for example, the displayed characters cannot be understood, and the display information itself cannot be seen (such as visually impaired persons). Even if it exists, it is possible to operate the mobile phone in accordance with the gesture as intended by the operator.

Therefore, it is possible to provide a mobile phone that does not place a burden on the operator's body and does not restrict the operation of the operator. In addition, the operator can provide a mobile phone that can be easily operated without directly touching the mobile phone.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 6)
In this embodiment, an example in which an operation recognition device having an imaging device to which the TOF method is applied is applied to an IH cooking heater will be described with reference to FIG. 15, and an example in which the motion recognition device is applied to a microwave oven will be described with reference to FIG.

FIG. 15 is a schematic configuration diagram of an IH cooking heater 6000 in which an imaging device is mounted on the display unit. It is also possible to mount the imaging device in a place other than the display unit of the IH cooking heater, and it is also possible to mount the imaging device in both the display unit of the IH cooking heater and the display unit. In any case, according to one embodiment of the disclosed invention, a three-dimensional distance image can be acquired by irradiating light (or infrared light) to an object to be detected.

In FIG. 15, the display unit of the IH cooking heater 6000 has a function of acquiring display information, a function of acquiring a three-dimensional distance image of the detection object, a function of acquiring color information of the detection object, and the like. Accordingly, since it is not necessary to provide a separate camera outside the IH cooking heater 6000, a simple configuration can be provided.

As shown in FIG. 15, the IH cooking heater 6000 includes display units 6001a, 6001b, 6001c, three-port IH heaters 6002a, 6002b, 6002c, a plate 6003, a power lamp 6004, operation buttons 6005, an exhaust port 6006, and the like. .

FIG. 15 shows an operation of the IH cooking heater 6000 by an operator's gesture (for example, a hand gesture) as an example. In the recognition ranges 6007a, 6007b, and 6007c, the operator can operate the IH cooking heater 6000 by performing a gesture without directly touching the IH cooking heater 6000.

Note that the recognition range 6007a is directly above the display portion 6001a, the recognition range 6007b is directly above the display portion 6001b, and the recognition range 6007c is directly above the display portion 6001c.

As shown in FIG. 15A, in the recognition range 6007a of the display unit 6001a, for example, when the operator performs an operation of “putting the thumb of the right hand and pushing forward”, the IH cooking heater 6000 is powered on. Enters and the power lamp 6004 is turned on.

As shown in FIG. 15B, in the recognition range 6007a of the display portion 6001a, for example, when the operator performs an operation of “holding the index finger and middle finger of the right hand and pushing forward”, the IH heater 6002a of the IH cooking heater 6000 Is turned off and the power lamp 6004 is turned off.

The operator can operate the IH cooking heater without directly touching the operation button 6005 or the display unit 6001 with a finger or the like. That is, the operator can perform various operations such as turning on / off the power of the IH heater, adjusting the heating power of the IH heater, and setting a timer for automatically turning off the power with only a gesture.

A specific object pattern is stored in the first storage unit mounted on the IH cooking heater 6000, and a specific operation pattern is stored in the second storage unit. Specific examples of the specific object pattern include “right thumb standing”, “right index finger and middle finger standing”, and the like. The specific object pattern may include color image information. When color image information is included, in addition to the finger shape pattern of the right hand, information such as finger color (skin color, etc.) and nail color (transparency, etc.) is also added. Further, specific operation patterns include an operation of “pushing the thumb of the right hand standing up”, an operation of “pushing the index finger and middle finger of the standing right hand forward”, and the like.

Note that the specific object pattern stored in the first storage unit and the specific operation pattern stored in the second storage unit may be arbitrarily determined by the operator. For example, when the operator performs an operation of “drawing a circle clockwise with the middle finger of the right hand”, an operation of “drawing a circle counterclockwise with the middle finger of the right hand” is performed. If the operator performs the setting of “IH cooking heater 6000 is turned off” or the operator performs the operation of “close both hands after putting both hands forward”, “double-sided automatic baking is performed on the grill of IH cooking heater 6000” If the operator performs an operation of “moving from left to right with one hand as a fist”, the setting of “the heating power of the IH cooking heater 6000 increases by one step”, etc. As described above, the operation corresponding to various patterns is preset by the operator so that the interface with the general-purpose control function and the media can be controlled. It is possible to realize an application to perform fine operation gesture.

Even if the operator's hand moves at high speed, the IH cooking heater 6000 can capture a three-dimensional distance image without distortion and easily acquire position change information and shape change information.

Note that the types of gestures are not limited to only gestures performed by an operator (human). You may employ | adopt the gesture imitating various objects, such as an object shape, a symbol, a character, and some object previously defined by the operator.

In the information processing apparatus mounted on the IH cooking heater 6000, processing is performed on the IH cooking heater so that the operation is reliably executed based on the specific operation pattern described above.

FIG. 16 is a schematic configuration diagram of a microwave oven 7000 in which an imaging device is mounted on the display unit. It is also possible to mount the imaging device in a place other than the display portion of the microwave oven, and it is also possible to mount the imaging device in both locations other than the display portion of the microwave oven and the display portion. In any case, according to one embodiment of the disclosed invention, it is possible to acquire a three-dimensional distance image by irradiating the detection object with light.

In FIG. 16, the display unit of the microwave oven 7000 has a function of acquiring display information, a function of acquiring a three-dimensional distance image of the detection object, and a function of acquiring color information of the detection object. Therefore, since it is not necessary to provide a separate camera outside the microwave oven 7000, a simple configuration can be provided.

As shown in FIG. 16, the microwave oven 7000 includes a display portion 7001, operation buttons 7002, a transparent viewing window 7003, an opening / closing door handle 7004, a housing 7005, an opening / closing door 7006, a power lamp 7008, and the like.

FIG. 16 shows an operation of the microwave oven 7000 by an operator's gesture (for example, hand gesture) as an example. In the recognition range 7007, the operator can operate the microwave oven 7000 by performing a gesture without directly touching the microwave oven 7000. Note that the recognition range 7007 is directly above the display portion 7001.

As shown in FIG. 16A, in the recognition range 7007 of the display portion 7001, for example, when the operator performs an operation of “moving from the top to the bottom with the left hand as a fist”, the microwave oven 7000 is turned on. The power lamp 7008 is lit ON.

For example, even when the operator's hand moves at high speed, the microwave oven 7000 can capture a three-dimensional distance image without distortion and easily acquire position change information and shape change information.

As shown in FIG. 16B, in the recognition range 7007 of the display portion 7001, for example, when the operator performs an operation of “moving from the bottom to the top with the left hand as a fist”, the microwave oven 7000 is turned off. The power lamp 7008 is turned off.

An operator can operate the microwave oven without directly touching the operation button 7002 or the display portion 7001 with a finger or the like. That is, the operator can perform all operations such as turning on / off the power source of the microwave oven, the oven function, and the steam function only by gestures.

Therefore, it is possible to provide an electronic device (IH cooking heater, microwave oven, etc.) that does not select the operator's state, does not put a burden on the operator's body, and does not restrict the operation of the operator. In addition, the operator can easily perform an operation without directly touching the electronic device.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 7)
In this embodiment, the structure of the photosensor 400 described in Embodiment 2 will be described in more detail. FIG. 17A is used for an example of a structure of an imaging device having photosensors 400 arranged in a matrix of m rows and n columns, and FIG. 17B is used for an example of a structure different from FIG. Will be described.

In FIG. 17A, a plurality of photosensors 400 are arranged in a matrix of m (m is a natural number of 2 or more) rows n (n is a natural number of 2 or more) columns. The photosensor 400 in each row includes any one of a plurality of signal lines 11 (PR) (represented as 11 (PR) _1 to 11 (PR) _m) and a plurality of signal lines 12 (TX) (12 (TX)). _1 to 12 (TX) _m) and one of the plurality of signal lines 13 (SE) (denoted as 13 (SE) _1 to 13 (SE) _m). Has been. The photosensor 400 in each column is electrically connected to any one of a plurality of photosensor output signal lines (denoted as 16_1 to 16_n) and any one of a plurality of photosensor reference signal lines (denoted as 15_1 to 15_n). Connected.

In FIG. 17A, the signal line 12 (TX) is shared by the photosensors of each row, the signal line 11 (PR) is shared by the photosensors of each row, and the signal line 13 (SE) is shared by the photosensors of each row. The photosensor output signal lines are shared by the photosensors in each column, and the photosensor reference signal lines are shared by the photosensors in each column. However, the present invention is not limited to this. A plurality of signal lines 12 (TX) may be provided in each row and electrically connected to different photosensors 400. A plurality of signal lines 11 (PR) may be provided in each row and electrically connected to different photosensors 400. A plurality of signal lines 13 (SE) may be provided in each row and electrically connected to different photosensors 400. A plurality of photosensor output signal lines may be provided in each column and electrically connected to different photosensors 400. A plurality of photosensor reference signal lines may be provided in each column and electrically connected to different photosensors 400.

FIG. 17A illustrates a structure in which the photosensor reference signal line is shared by the photosensors in each column; however, the present invention is not limited to this. The photo sensor reference signal line may be shared by the photo sensors in each row.

In addition, among the photosensors 400 arranged in a matrix of m rows and n columns, the signal line 12 (TX) can be shared by the photosensors 400 that perform the reset operation and the accumulation operation at the same time. Of the photosensors 400 arranged in a matrix of m rows and n columns, the signal line 11 (PR) can be shared by photosensors that perform the reset operation and the accumulation operation simultaneously.

By sharing wiring and reducing the number of wirings as described above, a driving circuit for driving the photosensors 400 arranged in a matrix of m rows and n columns can be simplified.

Next, an example of a structure different from that in FIG. 17A of the imaging device including the photosensors 400 arranged in a matrix of m rows and n columns is described with reference to FIG.

In FIG. 17B, a plurality of photosensors 400 are arranged in a matrix of m rows and n columns. The photosensor 400 in each row is electrically connected to any one of a plurality of signal lines 13 (SE) (denoted as 13 (SE) _1 to 13 (SE) _m). The photosensor 400 in each column includes any one of a plurality of signal lines 11 (PR) (indicated as 11 (PR) _1 to 11 (PR) _n) and a plurality of signal lines 12 (TX) (12 (TX) ) _1 to 12 (TX) _n), one of a plurality of photosensor output signal lines (represented as 16_1 to 16_n), and a plurality of photosensor reference signal lines (15_1 to 15_n). Is electrically connected to any one of them.

In FIG. 17B, the signal line 13 (SE) is shared by the photosensors of each row, the signal line 11 (PR) is shared by the photosensors of each column, and the signal line 12 (TX) is shared by the photosensors of each column. The photosensor output signal line is shared by the photosensors in each column, and the photosensor reference signal line is shared by the photosensors in each column. However, the present invention is not limited to this.

Although FIG. 17B illustrates a structure in which the photosensor reference signal line is shared by the photosensors in each column, the present invention is not limited to this. The photo sensor reference signal line may be shared by the photo sensors in each row.

In addition, among the photosensors 400 arranged in a matrix of m rows and n columns, the signal line 12 (TX) can be shared among the photosensors that perform the reset operation and the accumulation operation at the same time. Of the photosensors 400 arranged in a matrix of m rows and n columns, the signal line 11 (PR) can be shared by photosensors that perform the reset operation and the accumulation operation simultaneously.

By sharing wiring and reducing the number of wirings as described above, a driving circuit for driving the photosensors 400 arranged in a matrix of m rows and n columns can be simplified.

18A is a top view of the photosensor 400, and FIG. 18B is a cross-sectional view taken along dashed line A1-A2 in FIG.

The photosensor 400 includes a conductive film 210 functioning as the signal line 11 (PR), a conductive film 211 functioning as the signal line 12 (TX), a conductive film 212 functioning as the signal line 13 (SE), and the signal line 15. A conductive film 213 functioning as a (photosensor reference signal line) and a conductive film 214 functioning as a signal line 16 (photosensor output signal line) are provided.

A photodiode 402 included in the photosensor 400 includes a p-type semiconductor film 215, an i-type semiconductor film 216, and an n-type semiconductor film 217 that are sequentially stacked. The conductive film 210 is electrically connected to the p-type semiconductor film 215 that functions as the anode of the photodiode 402.

A conductive film 218 included in the photosensor 400 functions as a gate electrode of the transistor 403 and is electrically connected to the conductive film 211. A conductive film 219 included in the photosensor 400 functions as one of a source electrode and a drain electrode of the transistor 403. The conductive film 220 included in the photosensor 400 functions as the other of the source electrode and the drain electrode of the transistor 403. A conductive film 221 included in the photosensor 400 is electrically connected to the n-type semiconductor film 217 and the conductive film 219. A conductive film 222 included in the photosensor 400 functions as a gate electrode of the transistor 404 and is further electrically connected to the conductive film 220.

A conductive film 223 included in the photosensor 400 functions as one of a source electrode and a drain electrode of the transistor 404. A conductive film 224 included in the photosensor 400 functions as the other of the source electrode and the drain electrode of the transistor 404 and one of the source electrode and the drain electrode of the transistor 405. The conductive film 214 functions as the other of the source electrode and the drain electrode of the transistor 405. The conductive film 212 also functions as the gate electrode of the transistor 405. A conductive film 225 included in the photosensor 400 is electrically connected to the conductive films 223 and 213.

Note that in FIG. 18, the conductive film 226 included in the photosensor 400 is electrically connected to the conductive film 210 functioning as the signal line 11 (PR). In addition, the conductive film 227 included in the photosensor 400 is electrically connected to the conductive film 211 functioning as the signal line 12 (TX).

The conductive film 212, the conductive film 218, the conductive film 222, the conductive film 225, the conductive film 226, and the conductive film 227 can be formed by processing one conductive film formed over the insulating surface into a desired shape. . A gate insulating film 228 is formed over the conductive films 212, 218, 222, 225, 226, and 227. Further, the conductive film 210, the conductive film 211, the conductive film 213, the conductive film 214, the conductive film 219, the conductive film 220, the conductive film 223, and the conductive film 224 are preferably one conductive film formed over the gate insulating film 228. It can be formed by processing into the shape.

An insulating film 281 and an insulating film 282 are formed over the conductive film 210, the conductive film 211, the conductive film 213, the conductive film 214, the conductive film 219, the conductive film 220, the conductive film 223, and the conductive film 224. . A conductive film 221 is formed over the insulating film 281 and the insulating film 282.

An oxide semiconductor is preferably used for the semiconductor layer 250 of the transistor 403. In order to hold the charge generated by light irradiation from the substrate 251 side for a long time, the transistor 403 electrically connected to the photodiode 402 needs to be formed using a transistor with extremely low off-state current. is there. Therefore, the performance of the photosensor 400 can be improved by using an oxide semiconductor material for the semiconductor layer 250. Note that an oxide semiconductor can be used as a semiconductor layer used in the transistor 404 and the transistor 405.

Alternatively, a material such as amorphous silicon, microcrystalline silicon, polycrystalline silicon, or single crystal silicon can be used for the semiconductor layer used in the transistor 404 and the transistor 405. By using these materials, a transistor with high mobility can be formed.

Note that in the case where the transistor 403 is a bottom-gate transistor, a structure in which the semiconductor layer 250 completely overlaps with the conductive film 218 functioning as the gate electrode is preferably used as illustrated in FIG. By employing the above structure, the oxide semiconductor in the semiconductor layer 250 is prevented from being deteriorated by light incident from the substrate 251 side, and thus deterioration of characteristics such as shift of the threshold voltage of the transistor 403 is caused. Can be prevented. Note that the same effect can be obtained for the transistor 404 and the transistor 405 by adopting the above structure.

Here, in the configuration in which the signal line 12 (TX) as illustrated in FIG. 17A extends in the row direction, the signal line 12 (TX) also extends in the row direction and is parallel to the signal line 12 (TX). A signal line 13 (SE) exists. Since the signal line 13 (SE) is electrically connected to the gate electrode of the transistor 405, if a part of the signal line 13 (SE) is used as the gate electrode of the transistor 405, a signal parallel to the signal line 13 (SE) is used. The line 12 (TX) is generally formed in the same layer as the gate electrode of the transistor 405 using the same material as the gate electrode. However, a material used for a gate electrode of a transistor is generally a material having higher resistance than a material used for a source electrode or a drain electrode. For this reason, the resistance of the signal line 12 (TX) tends to increase.

On the other hand, in the configuration illustrated in FIG. 17B, the signal line 12 (TX) extends in the column direction. Therefore, the signal line 12 (TX) can be formed using a conductive film formed in a layer different from the signal line 13 (SE) arranged extending in the row direction. For example, as illustrated in FIG. 18, conductive films (conductive film 212, conductive film 218, and conductive film 222) that form gate electrodes of transistors (transistor 403, transistor 404, transistor 405, and the like) included in the photosensor 400 The signal line 12 (TX) can be formed by the conductive films 211 formed in different layers. The conductive film 211 is formed in the same layer as the source electrode or the drain electrode of the transistor (the transistor 403, the transistor 404, the transistor 405, or the like) included in the photosensor 400, such as the conductive film 214, the conductive film 219, the conductive film 220, and the conductive film 224. It can be formed using the same material as the source electrode and the drain electrode. Therefore, the resistance of the signal line 12 (TX) can be reduced as compared with the structure illustrated in FIG.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 8)
In this embodiment, a method for manufacturing a photosensor including a transistor in which a channel is formed in a semiconductor film such as single crystal silicon and a transistor in which a channel is formed in an oxide semiconductor layer will be described.

As shown in FIG. 19A, a photodiode 7040 and an n-channel transistor 7050 are formed over an insulating surface of a substrate 7060 using a known CMOS manufacturing method. In this embodiment, the case where the photodiode 7040 and the n-channel transistor 7050 are formed using a single crystal semiconductor film separated from a single crystal semiconductor substrate is given as an example. As the single crystal semiconductor substrate, for example, a silicon substrate can be used.

An example of a specific method for manufacturing a single crystal semiconductor film will be briefly described. First, an ion beam made of ions accelerated by an electric field is injected into a single crystal semiconductor substrate, and the crystal structure is disturbed locally from the surface of the semiconductor substrate to a certain depth. Forming a brittle layer. The depth of the region where the embrittlement layer is formed can be adjusted by the acceleration energy of the ion beam and the incident angle of the ion beam. Then, the semiconductor substrate and the substrate 7060 over which the insulating film 7010 is formed are attached so that the insulating film 7010 is sandwiched therebetween. In the bonding, after the semiconductor substrate and the substrate 7060 are overlapped, part of the semiconductor substrate and the substrate 7060 is 1 N / cm ² or more and 500 N / cm ² or less, preferably 11 N / cm ² or more and 20 N / cm ² or less. Apply pressure. When pressure is applied, the semiconductor substrate and the insulating film 7010 start to be joined from that portion, and finally the whole surface is joined. Next, by performing heat treatment, the microvoids existing in the embrittled layer are combined with each other, and the volume of the microvoids is increased. As a result, the single crystal semiconductor film which is part of the semiconductor substrate in the embrittlement layer is separated from the semiconductor substrate. The temperature for the heat treatment is set so as not to exceed the strain point of the substrate 7060. Then, the single crystal semiconductor film is processed into a desired shape by etching or the like, whereby the island-shaped semiconductor film 7020 and the island-shaped semiconductor film 7030 can be formed.

The photodiode 7040 is formed using the island-shaped semiconductor film 7020 over the insulating film 7010, and the n-channel transistor 7050 is formed using the island-shaped semiconductor film 7030 over the insulating film 7010. In the photodiode 7040, a region 7270 having p-type conductivity, a region 7280 having i-type conductivity, and a region 7290 having n-type conductivity are formed in an island-shaped semiconductor film 7020. Horizontal type. Further, the n-channel transistor 7050 includes a gate electrode 7070. The n-channel transistor 7050 includes a pair of n-type conductive regions provided in the island-shaped semiconductor film 7030 so as to sandwich a region overlapping with the gate electrode 7070. The n-channel transistor 7050 includes an insulating film 7080 between the island-shaped semiconductor film 7030 and the gate electrode 7070. In the n-channel transistor 7050, the insulating film 7080 functions as a gate insulating film.

Note that in the region 7280 having i-type conductivity, the impurity imparting p-type or n-type contained in the semiconductor film has a concentration of 1 × 10 ²⁰ cm ⁻³ or less, and light with respect to dark conductivity It refers to the region where the conductivity is 400 times or more. The region 7280 having i-type conductivity includes a region having an impurity element belonging to Group 13 or Group 15 of the periodic table in its category. That is, since the region 7280 having i-type conductivity exhibits weak n-type conductivity when an impurity element for the purpose of controlling valence electrons is not intentionally added, the region 7280 having i-type conductivity is provided. Includes in its category an impurity element imparting p-type intentionally or unintentionally added during or after film formation.

There is no particular limitation on a material that can be used as the substrate 7060; however, in the case where a transmissive or transflective liquid crystal element is used, the substrate 7060 is also a light-transmitting material. In addition, a material that can be used as the substrate 7060 needs to have at least heat resistance enough to withstand heat treatment performed later. For example, for the substrate 7060, a glass substrate, a quartz substrate, a ceramic substrate, or the like manufactured by a fusion method or a float method can be used. As the glass substrate, a glass substrate having a strain point of 730 ° C. or higher is preferably used when the temperature of the subsequent heat treatment is high. A substrate made of a synthetic resin having flexibility such as plastic generally tends to have a lower heat resistant temperature than the above substrate, but can be used as long as it can withstand the processing temperature in the manufacturing process. .

Note that although an example in which the photodiode 7040 and the n-channel transistor 7050 are formed using a single crystal semiconductor film is described in this embodiment, the present invention is not limited to this structure. For example, a polycrystalline or microcrystalline semiconductor film formed over the insulating film 7010 by a vapor deposition method may be used, or the semiconductor film may be crystallized by a known technique. Known crystallization methods include a laser crystallization method using laser light and a crystallization method using a catalytic element. Alternatively, a crystallization method using a catalytic element and a laser crystallization method can be used in combination. In addition, when using a substrate having excellent heat resistance such as quartz, a thermal crystallization method using an electric furnace, a lamp annealing crystallization method using infrared light, a crystallization method using a catalytic element, about 950 ° C. Alternatively, a crystallization method combining the high temperature annealing method may be used.

As shown in FIG. 19A, after a conductive film is formed over the insulating film 7080, the conductive film is processed into a desired shape by etching or the like, whereby the wiring 7110 is formed together with the gate electrode 7070. .

Next, as illustrated in FIG. 19A, an insulating film 7120 is formed so as to cover the photodiode 7040, the n-channel transistor 7050, the wiring 7110, and the gate electrode 7070. Note that although the case where the single-layer insulating film 7120 is used is illustrated in this embodiment, the insulating film 7120 is not necessarily a single layer, and two or more insulating films are stacked to form the insulating film 7120. It may be used.

The insulating film 7120 is formed using a material that can withstand the temperature of heat treatment in a later manufacturing process. Specifically, it is preferable to use a material such as silicon oxide, silicon nitride, silicon nitride oxide, silicon oxynitride, aluminum nitride, or aluminum oxide for the insulating film 7120.

Note that in this specification, oxynitride is a substance having a higher oxygen content than nitrogen in the composition, and nitride oxide has a nitrogen content higher than oxygen in the composition. Means a substance.

The surface of the insulating film 7120 may be planarized by a CMP method or the like.

Next, as illustrated in FIG. 19A, a gate electrode 7130 is formed over the insulating film 7120.

The material of the gate electrode 7130 is a metal material such as molybdenum, titanium, chromium, tantalum, tungsten, neodymium, or scandium, an alloy material containing these metal materials as a main component, or a nitride of these metals in a single layer or a stacked layer. Can be used. Note that aluminum or copper can also be used as the metal material as long as it can withstand the temperature of heat treatment performed in a later step. Aluminum or copper is preferably used in combination with a refractory metal material in order to avoid heat resistance and corrosion problems. As the refractory metal material, molybdenum, titanium, chromium, tantalum, tungsten, neodymium, scandium, or the like can be used.

For example, as the gate electrode 7130 having a two-layer structure, a two-layer structure in which a molybdenum film is stacked on an aluminum film, a two-layer structure in which a molybdenum film is stacked on a copper film, and a titanium nitride film on the copper film Alternatively, a two-layer structure in which a tantalum nitride film is stacked or a two-layer structure in which a titanium nitride film and a molybdenum film are stacked is preferable. As the gate electrode 7130 having a three-layer structure, an aluminum film, an aluminum-silicon alloy film, an aluminum-titanium alloy film, or an aluminum-neodymium alloy film is used as an intermediate layer, and a tungsten film, a tungsten nitride film, or a titanium nitride film is used. A structure in which a film or a titanium film is laminated as upper and lower layers is preferable.

Alternatively, the gate electrode 7130 may be formed using a light-transmitting oxide conductive film such as indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, zinc aluminum oxide, zinc aluminum oxynitride, or zinc gallium oxide. it can.

The thickness of the gate electrode 7130 is 10 nm to 400 nm, preferably 40 nm to 200 nm. In this embodiment, after forming a conductive film for a gate electrode with a thickness of 150 nm by a sputtering method using a tungsten target, the conductive film is processed (patterned) into a desired shape by etching, whereby the gate electrode 7130 is formed. To do. Note that it is preferable that the formed gate electrode has a tapered shape because coverage with a gate insulating film stacked thereover is improved. Note that the resist mask may be formed by an inkjet method. When the resist mask is formed by an ink-jet method, a manufacturing cost can be reduced because a photomask is not used.

Next, as illustrated in FIG. 19B, after the gate insulating film 7140 is formed over the gate electrode 7130, the oxide semiconductor layer 7150 is formed in a position overlapping with the gate electrode 7130 over the gate insulating film 7140.

The gate insulating film 7140 is formed using a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon nitride oxide film, an aluminum oxide film, an aluminum nitride film, an aluminum oxynitride film, a oxynitride oxide, using a plasma CVD method, a sputtering method, or the like. An aluminum film, a hafnium oxide film, or a tantalum oxide film can be formed as a single layer or stacked layers. The gate insulating film 7140 preferably contains as little moisture, impurities as hydrogen and oxygen as possible. In the case of forming a silicon oxide film by a sputtering method, a silicon target or a quartz target is used as a target, and oxygen or a mixed gas of oxygen and argon is used as a sputtering gas.

An oxide semiconductor layer that is i-type or substantially i-type by removing impurities (a highly purified oxide semiconductor layer) is extremely sensitive to interface states and interface charges. The interface between the purified oxide semiconductor layer 7150 and the gate insulating film 7140 is important. The gate insulating film 7140 in contact with the oxide semiconductor layer 7150 is required to have high quality.

For example, a high-density plasma CVD method using μ-wave (frequency: 2.45 GHz) is preferable because a high-quality insulating film with high density and high withstand voltage can be formed. When the highly purified oxide semiconductor layer and the high-quality gate insulating film are in close contact with each other, the interface state can be reduced and interface characteristics can be improved.

Needless to say, another film formation method such as a sputtering method or a plasma CVD method can be employed as long as a high-quality insulating film can be formed as the gate insulating film 7140. Alternatively, an insulating film whose film quality or interface characteristics with the oxide semiconductor layer 7150 is improved by heat treatment after film formation may be used. In any case, any film can be used as long as it can reduce the interface state density between the gate insulating film and the oxide semiconductor layer and form a good interface, as well as having good film quality as the gate insulating film. .

The gate insulating film 7140 may have a structure in which an insulating film using a material having a high barrier property and an insulating film such as a silicon oxide film or a silicon oxynitride film with a low nitrogen content are stacked. In this case, an insulating film such as a silicon oxide film or a silicon oxynitride film is formed between the insulating film having a high barrier property and the oxide semiconductor layer. As the insulating film having a high barrier property, for example, a silicon nitride film, a silicon nitride oxide film, an aluminum nitride film, an aluminum nitride oxide film, or the like can be given. By forming the insulating film using a material having a high barrier property, impurities in an atmosphere such as moisture or hydrogen, or impurities such as alkali metals and heavy metals contained in the substrate are formed in the oxide semiconductor layer, the gate insulating film 7140, or the interface between the oxide semiconductor layer and another insulating film and the vicinity thereof can be prevented. In addition, by forming an insulating film such as a silicon oxide film or a silicon oxynitride film having a low nitrogen content so as to be in contact with the oxide semiconductor layer, the insulating film having a high barrier property can be in direct contact with the oxide semiconductor layer. Can be prevented.

For example, a silicon nitride film (SiN _y (y> 0)) with a thickness of 50 nm to 200 nm is formed as the first gate insulating film by a sputtering method, and the second gate insulating film is formed over the first gate insulating film. A gate insulating film 7140 with a thickness of 400 nm may be formed by stacking silicon oxide films (SiO _x (x> 0)) with a thickness of 5 nm to 300 nm. The thickness of the gate insulating film 7140 may be set as appropriate depending on characteristics required for the transistor, and may be approximately 350 nm to 400 nm.

In this embodiment, the gate insulating film 7140 having a structure in which a silicon oxide film with a thickness of 400 nm formed by a sputtering method is stacked over a silicon nitride film with a thickness of 50 nm formed by a sputtering method is formed. .

Note that the gate insulating film 7140 is in contact with an oxide semiconductor layer to be formed later. Since the oxide semiconductor adversely affects characteristics when hydrogen is contained, it is preferable that the gate insulating film 7140 be free of hydrogen, a hydroxyl group, and moisture. In order to prevent the gate insulating film 7140 from containing hydrogen, a hydroxyl group, and moisture as much as possible, as a pretreatment for film formation, the substrate 7060 over which the gate electrode 7130 is formed is preheated in a preheating chamber of a sputtering apparatus, and It is preferable that impurities such as moisture or hydrogen adsorbed on the substrate 7060 be desorbed and exhausted. Note that the preheating temperature is 100 ° C. or higher and 400 ° C. or lower, preferably 150 ° C. or higher and 300 ° C. or lower. Note that a cryopump is preferable as an exhaustion unit provided in the preheating chamber. Note that this preheating treatment can be omitted.

The oxide semiconductor layer 7150 can be formed by processing an oxide semiconductor film formed over the gate insulating film 7140 into a desired shape. The thickness of the oxide semiconductor film is 2 nm to 200 nm, preferably 3 nm to 50 nm, more preferably 3 nm to 20 nm. The oxide semiconductor film is formed by a sputtering method using an oxide semiconductor as a target. The oxide semiconductor film can be formed by a sputtering method in a rare gas (eg, argon) atmosphere, an oxygen atmosphere, or a rare gas (eg, argon) and oxygen mixed atmosphere.

Note that before the oxide semiconductor film is formed by a sputtering method, reverse sputtering in which an argon gas is introduced to generate plasma is preferably performed to remove dust attached to the surface of the gate insulating film 7140. Reverse sputtering is a method of modifying the surface by forming a plasma near the substrate by applying a voltage using an RF power source on the substrate side in an argon atmosphere without applying a voltage to the target side. Note that an atmosphere such as nitrogen or helium may be used instead of the argon atmosphere. Alternatively, an argon atmosphere may be used in which oxygen, nitrous oxide, or the like is added. Alternatively, the reaction may be performed in an atmosphere in which chlorine, carbon tetrafluoride, or the like is added to an argon atmosphere.

The oxide semiconductor film preferably contains at least indium (In) or zinc (Zn). In particular, In and Zn are preferably included. In addition, it is preferable that gallium (Ga) be included in addition to the stabilizer for reducing variation in electrical characteristics of the transistor including the oxide semiconductor film. Moreover, it is preferable to have tin (Sn) as a stabilizer. Moreover, it is preferable to have hafnium (Hf) as a stabilizer. Moreover, it is preferable to have aluminum (Al) as a stabilizer.

Other stabilizers include lanthanoids such as lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb). , Dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), or lutetium (Lu).

For example, as an oxide semiconductor, indium oxide, tin oxide, zinc oxide, binary metal oxides such as In—Zn oxide, Sn—Zn oxide, Al—Zn oxide, Zn—Mg oxide Oxides, Sn—Mg oxides, In—Mg oxides, In—Ga oxides, In—Ga—Zn oxides (also referred to as IGZO) which are oxides of ternary metals, In— Al-Zn oxide, In-Sn-Zn oxide, Sn-Ga-Zn oxide, Al-Ga-Zn oxide, Sn-Al-Zn oxide, In-Hf-Zn oxide In-La-Zn-based oxide, In-Ce-Zn-based oxide, In-Pr-Zn-based oxide, In-Nd-Zn-based oxide, In-Sm-Zn-based oxide, In-Eu -Zn oxide, In-Gd-Zn oxide, In-Tb-Zn oxide, n-Dy-Zn-based oxide, In-Ho-Zn-based oxide, In-Er-Zn-based oxide, In-Tm-Zn-based oxide, In-Yb-Zn-based oxide, In-Lu-Zn -Based oxides, In-Sn-Ga-Zn-based oxides that are oxides of quaternary metals, In-Hf-Ga-Zn-based oxides, In-Al-Ga-Zn-based oxides, In-Sn- An Al—Zn-based oxide, an In—Sn—Hf—Zn-based oxide, or an In—Hf—Al—Zn-based oxide can be used.

Note that here, for example, an In—Ga—Zn-based oxide means an oxide containing In, Ga, and Zn as its main components, and there is no limitation on the ratio of In, Ga, and Zn. Moreover, metal elements other than In, Ga, and Zn may be contained.

For example, In: Ga: Zn = 1: 1: 1 (= 1/3: 1/3: 1/3) or In: Ga: Zn = 2: 2: 1 (= 2/5: 2/5: 1). / 5) atomic ratio In—Ga—Zn-based oxides and oxides in the vicinity of the composition can be used. Alternatively, In: Sn: Zn = 1: 1: 1 (= 1/3: 1/3: 1/3), In: Sn: Zn = 2: 1: 3 (= 1/3: 1/6: 1) / 2) or In: Sn: Zn = 2: 1: 5 (= 1/4: 1/8: 5/8) atomic ratio In—Sn—Zn-based oxide or an oxide in the vicinity of the composition. Can be used.

However, the composition is not limited to those described above, and a material having an appropriate composition may be used depending on required electrical characteristics (such as mobility, threshold value, and variation) of a semiconductor. In order to obtain the required electrical characteristics of the semiconductor, it is preferable that the carrier concentration, impurity concentration, defect density, atomic ratio of metal element to oxygen, interatomic distance, density, and the like are appropriate.

The oxide semiconductor may be single crystal or non-single crystal. In the latter case, it may be amorphous or polycrystalline. Moreover, the structure which contains the part which has crystallinity in an amorphous may be sufficient, and a non-amorphous may be sufficient.

In this embodiment, a 30 nm-thick In—Ga—Zn-based oxide semiconductor thin film obtained by sputtering using a target containing In (indium), Ga (gallium), and Zn (zinc) is oxidized. Used as a physical semiconductor film. As the target, for example, the composition of each metal is In: Ga: Zn = 1: 1: 0.5, In: Ga: Zn = 1: 1: 1, or In: Ga: Zn = 1: 1: 2. A certain target can be used. The filling rate of the target containing In, Ga, and Zn is 90% to 100%, preferably 95% to less than 100%. By using a target with a high filling rate, the formed oxide semiconductor film becomes a dense film.

In this embodiment mode, the substrate is held in a processing chamber held in a reduced pressure state, a sputtering gas from which hydrogen and moisture are removed is removed while residual moisture in the processing chamber is removed, and the substrate 7060 is formed using the above target. An oxide semiconductor film is formed. At the time of film formation, the substrate temperature may be 100 ° C. or higher and 600 ° C. or lower, preferably 200 ° C. or higher and 400 ° C. or lower. By forming the film while heating the substrate, the concentration of impurities contained in the formed oxide semiconductor film can be reduced. Further, damage due to sputtering is reduced. In order to remove moisture remaining in the treatment chamber, an adsorption-type vacuum pump is preferably used. For example, it is preferable to use a cryopump, an ion pump, or a titanium sublimation pump. The exhaust means may be a turbo pump provided with a cold trap. When a processing chamber is exhausted using a cryopump, for example, a compound containing a hydrogen atom (more preferably a compound containing a carbon atom) such as a hydrogen atom or water (H ₂ O) is exhausted. The concentration of impurities contained in the formed oxide semiconductor film can be reduced.

As an example of film forming conditions, a distance between the substrate and the target is 400 mm, a pressure is 0.6 Pa, a direct current (DC) power source is 0.5 kW, and an oxygen (oxygen flow rate ratio: 100%) atmosphere is applied. Note that a pulse direct current (DC) power source is preferable because dust generated in film formation can be reduced and the film thickness can be made uniform.

Note that in order to prevent the oxide semiconductor film from containing hydrogen, a hydroxyl group, and moisture as much as possible, a substrate 7060 over which the gate insulating film 7140 is formed in a preheating chamber of a sputtering apparatus is preliminarily used as a pretreatment for film formation. It is preferable to heat and desorb impurities such as moisture or hydrogen adsorbed on the substrate 7060 and exhaust. Note that the preheating temperature is 100 ° C. or higher and 400 ° C. or lower, preferably 150 ° C. or higher and 300 ° C. or lower. In addition, a cryopump is preferable as the exhaust means provided in the preheating chamber. Note that this preheating treatment can be omitted. Further, this preheating may be similarly performed on the substrate 7060 on which the conductive film 7200 and the conductive film 7210 are formed before the insulating film 7220 to be formed later.

Note that etching for forming the oxide semiconductor layer 7150 may be dry etching or wet etching, or both of them may be used. As an etching gas used for dry etching, a gas containing chlorine (chlorine-based gas such as chlorine (Cl ₂ ), boron trichloride (BCl ₃ ), silicon tetrachloride (SiCl ₄ ), carbon tetrachloride (CCl ₄ ), or the like) Is preferred. Gas containing fluorine (fluorine-based gas such as carbon tetrafluoride (CF ₄ ), sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), trifluoromethane (CHF ₃ ), etc.), bromide Hydrogen (HBr), oxygen (O ₂ ), a gas obtained by adding a rare gas such as helium (He) or argon (Ar) to these gases, or the like can be used.

As the dry etching method, a parallel plate RIE (Reactive Ion Etching) method or an ICP (Inductively Coupled Plasma) etching method can be used. Etching conditions (such as the amount of power applied to the coil-type electrode, the amount of power applied to the substrate-side electrode, the substrate-side electrode temperature, etc.) are adjusted as appropriate so that the desired processed shape can be etched.

As an etchant used for wet etching, a mixed solution of phosphoric acid, acetic acid, and nitric acid, or an organic acid such as citric acid or oxalic acid can be used. In this embodiment, ITO-07N (manufactured by Kanto Chemical Co., Inc.) is used.

A resist mask for forming the oxide semiconductor layer 7150 may be formed by an inkjet method. When the resist mask is formed by an ink-jet method, a manufacturing cost can be reduced because a photomask is not used.

Note that before the conductive film in the next step is formed, reverse sputtering is preferably performed to remove a resist residue or the like attached to the surfaces of the oxide semiconductor layer 7150 and the gate insulating film 7140.

Note that an oxide semiconductor layer formed by sputtering or the like may contain a large amount of moisture or hydrogen (including a hydroxyl group) as an impurity. Since moisture or hydrogen easily forms a donor level, it is an impurity for an oxide semiconductor. Therefore, in one embodiment of the present invention, in order to reduce (dehydrate or dehydrogenate) impurities such as moisture or hydrogen in the oxide semiconductor layer, nitrogen or Moisture content when measured using an inert gas atmosphere such as a rare gas, an oxygen gas atmosphere, or an ultra-dry air (CRDS (cavity ring down laser spectroscopy) type dew point meter) is 20 ppm (-55 in terms of dew point) ° C) or less, preferably 1 ppm or less, preferably 10 ppb or less of air) under an atmosphere.

By performing heat treatment on the oxide semiconductor layer 7150, moisture or hydrogen in the oxide semiconductor layer 7150 can be eliminated. Specifically, heat treatment may be performed at a temperature of 250 ° C. to 750 ° C., preferably 400 ° C. to less than the strain point of the substrate. For example, it may be performed at 500 ° C. for about 3 minutes to 6 minutes. When the RTA method is used for the heat treatment, dehydration or dehydrogenation can be performed in a short time, and thus the treatment can be performed even at a temperature exceeding the strain point of the glass substrate.

In this embodiment, an electric furnace which is one of heat treatment apparatuses is used.

Note that the heat treatment apparatus is not limited to an electric furnace, and may include a device for heating an object to be processed by heat conduction or heat radiation from a heating element such as a resistance heating element. For example, an RTA (Rapid Thermal Annealing) device such as a GRTA (Gas Rapid Thermal Annealing) device or an LRTA (Lamp Rapid Thermal Annealing) device can be used. The LRTA apparatus is an apparatus that heats an object to be processed by radiation of light (electromagnetic waves) emitted from a lamp such as a halogen lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp, a high pressure sodium lamp, or a high pressure mercury lamp. The GRTA apparatus is an apparatus that performs heat treatment using a high-temperature gas. As the gas, an inert gas that does not react with an object to be processed by heat treatment, such as nitrogen or a rare gas such as argon, is used.

Note that in the heat treatment, moisture, hydrogen, or the like is preferably not contained in nitrogen or a rare gas such as helium, neon, or argon. Alternatively, the purity of nitrogen or a rare gas such as helium, neon, or argon introduced into the heat treatment apparatus is 6N (99.9999%) or more, preferably 7N (99.99999%) or more (that is, the impurity concentration is 1 ppm). Or less, preferably 0.1 ppm or less).

Through the above steps, the concentration of hydrogen in the oxide semiconductor layer 7150 can be reduced and the oxide semiconductor layer 7150 can be highly purified. Accordingly, stabilization of the oxide semiconductor layer 7150 can be achieved. In addition, the oxide semiconductor layer 7150 having an extremely low carrier density and a wide band gap can be formed by heat treatment at a glass transition temperature or lower. Therefore, a transistor can be manufactured using a large-area substrate, and mass productivity can be improved. Further, with the use of the oxide semiconductor layer 7150 with high purity and reduced hydrogen concentration, a transistor with high withstand voltage and extremely low off-state current can be manufactured. The heat treatment can be performed at any time after the oxide semiconductor film is formed.

Note that in the case of heating an oxide semiconductor film, a plate-like crystal may be formed on the surface of the oxide semiconductor film, depending on a material of the oxide semiconductor film and heating conditions. The plate-like crystal is preferably a single crystal having a c-axis orientation substantially perpendicular to the surface of the oxide semiconductor film. Further, even if not a single crystal body, the ab planes of the respective crystals coincide in the channel formation region, or the a-axis or the b-axis coincide with each other, and c is substantially perpendicular to the surface of the oxide semiconductor film. An axially oriented polycrystal is preferred. Note that in the case where the base surface of the oxide semiconductor film is uneven, the plate-like crystal is a polycrystal. Therefore, it is desirable that the underlying surface be as flat as possible.

An oxide semiconductor film is in a single crystal state, a polycrystalline (also referred to as polycrystal) state, an amorphous state, or the like.

The oxide semiconductor film is preferably a CAAC-OS (C Axis Crystallized Oxide Semiconductor) film. The CAAC-OS film is not completely single crystal nor completely amorphous. The CAAC-OS film is an oxide semiconductor film with a crystal-amorphous mixed phase structure where crystal parts and amorphous parts are included in an amorphous phase. Note that the crystal part is often large enough to fit in a cube whose one side is less than 100 nm. Further, in the observation image obtained by a transmission electron microscope (TEM), the boundary between the amorphous part and the crystal part included in the CAAC-OS film is not clear. Further, a grain boundary (also referred to as a grain boundary) cannot be confirmed in the CAAC-OS film by TEM. Therefore, in the CAAC-OS film, reduction in electron mobility due to grain boundaries is suppressed.

The crystal part included in the CAAC-OS film is triangular when viewed from the direction perpendicular to the ab plane and the c-axis is aligned in a direction parallel to the normal vector of the formation surface of the CAAC-OS film or the normal vector of the surface. It has a shape or hexagonal atomic arrangement, and metal atoms are arranged in layers or metal atoms and oxygen atoms are arranged in layers as viewed from the direction perpendicular to the c-axis. Note that the directions of the a-axis and the b-axis may be different between different crystal parts. In this specification, a simple term “perpendicular” includes a range from 85 ° to 95 °. In addition, a simple term “parallel” includes a range from −5 ° to 5 °.

Note that the distribution of crystal parts in the CAAC-OS film is not necessarily uniform. For example, in the formation process of the CAAC-OS film, when crystal growth is performed from the surface side of the oxide semiconductor film, the ratio of crystal parts in the vicinity of the surface of the oxide semiconductor film is higher in the vicinity of the surface. In addition, when an impurity is added to the CAAC-OS film, the crystal part in a region to which the impurity is added becomes amorphous in some cases.

Since the c-axis of the crystal part included in the CAAC-OS film is aligned in a direction parallel to the normal vector of the formation surface of the CAAC-OS film or the normal vector of the surface, the shape of the CAAC-OS film (formation surface) Depending on the cross-sectional shape or the cross-sectional shape of the surface). Note that the c-axis direction of the crystal part is parallel to the normal vector of the surface where the CAAC-OS film is formed or the normal vector of the surface. The crystal part is formed by film formation or by performing crystallization treatment such as heat treatment after film formation.

In a transistor using a CAAC-OS film, change in electrical characteristics due to irradiation with visible light or ultraviolet light is small. Therefore, the transistor has high reliability.

Note that part of oxygen included in the oxide semiconductor film may be replaced with nitrogen.

Next, the insulating film 7080, the insulating film 7120, and the gate insulating film 7140 are partially etched, so that contact holes reaching the island-shaped semiconductor film 7020, the island-shaped semiconductor film 7030, and the wiring 7110 are formed.

Then, after a conductive film is formed by a sputtering method or a vacuum evaporation method so as to cover the oxide semiconductor layer 7150, the conductive film is patterned by etching or the like, whereby a source electrode is formed as shown in FIG. A conductive film 7160, a conductive film 7170, a conductive film 7180, a conductive film 7190, a conductive film 7200, and a conductive film 7210 functioning as a drain electrode or a wiring are formed.

Note that the conductive films 7160 and 7170 are in contact with the island-shaped semiconductor film 7020. The conductive films 7180 and 7190 are in contact with the island-shaped semiconductor film 7030. The conductive film 7200 is in contact with the wiring 7110 and the oxide semiconductor layer 7150. The conductive film 7210 is in contact with the oxide semiconductor layer 7150.

As a material of the conductive film to be the conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, and the conductive film 7210, an element selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, and tungsten Or an alloy containing the above-described element as a component, an alloy film combining the above-described elements, or the like. Alternatively, a high melting point metal film such as chromium, tantalum, titanium, molybdenum, or tungsten may be stacked below or above the metal film such as aluminum or copper. Aluminum or copper is preferably used in combination with a refractory metal material in order to avoid problems of heat resistance and corrosion. As the refractory metal material, molybdenum, titanium, chromium, tantalum, tungsten, neodymium, scandium, yttrium, or the like can be used.

The conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, and the conductive film 7210 may have a single-layer structure or a stacked structure of two or more layers. For example, a single-layer structure of an aluminum film containing silicon, a two-layer structure in which a titanium film is stacked on an aluminum film, a titanium film, an aluminum film stacked on the titanium film, and a titanium film stacked on the titanium film And a three-layer structure.

Alternatively, the conductive film to be the conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, and the conductive film 7210 may be formed using a conductive metal oxide. As the conductive metal oxide, indium oxide, tin oxide, zinc oxide, indium tin oxide, indium zinc oxide, or a metal oxide material containing silicon or silicon oxide can be used.

In the case where heat treatment is performed after formation of the conductive film, the conductive film preferably has heat resistance enough to withstand the heat treatment.

Note that each material and etching conditions are adjusted as appropriate so that the oxide semiconductor layer 7150 is not removed as much as possible when the conductive film is etched. Depending on the etching conditions, the exposed portion of the island-shaped oxide semiconductor layer 7150 is partly etched, so that a groove (a depressed portion) may be formed.

In this embodiment, a titanium film is used for the conductive film. Therefore, the conductive film can be selectively wet etched using a solution containing ammonia and aqueous hydrogen peroxide (ammonia hydrogen peroxide), but the oxide semiconductor layer 7150 is also partially etched. Specifically, the ammonia overwater uses an aqueous solution in which 31% by weight of hydrogen peroxide water, 28% by weight of ammonia water and water are mixed at a volume ratio of 5: 2: 2. Alternatively, the conductive film may be dry-etched using a gas containing chlorine (Cl ₂ ), boron trichloride (BCl ₃ ), or the like.

Note that in order to reduce the number of photomasks used in the photolithography process and the number of processes, the etching process may be performed using a resist mask formed by a multi-tone mask that gives multi-level intensity to transmitted light. A resist mask formed using a multi-tone mask has a shape with a plurality of thicknesses, and the shape can be further deformed by etching. Therefore, the resist mask can be used for a plurality of etching processes for processing into different patterns. . Therefore, a resist mask corresponding to at least two kinds of different patterns can be formed by using one multi-tone mask. Therefore, the number of exposure masks can be reduced, and the corresponding photolithography process can be reduced, so that the process can be simplified.

Next, plasma treatment using a gas such as N ₂ O, N ₂ , or Ar is performed. Water or the like attached to the surface of the oxide semiconductor layer 7150 exposed by this plasma treatment is removed. Further, plasma treatment may be performed using a mixed gas of oxygen and argon.

Note that after the plasma treatment, as illustrated in FIG. 19C, the conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, the conductive film 7210, and the oxide semiconductor layer 7150 An insulating film 7220 is formed so as to cover the surface. The insulating film 7220 preferably contains as little moisture, impurities as hydrogen and oxygen, and may be a single-layer insulating film or a plurality of stacked insulating films. When hydrogen is contained in the insulating film 7220, the hydrogen penetrates into the oxide semiconductor layer, or hydrogen extracts oxygen in the oxide semiconductor layer, so that the back channel portion of the oxide semiconductor layer has low resistance (n-type reduction). And a parasitic channel may be formed. Therefore, it is important not to use hydrogen in the deposition method so that the insulating film 7220 contains as little hydrogen as possible. It is preferable to use a material having a high barrier property for the insulating film 7220. For example, a silicon nitride film, a silicon nitride oxide film, an aluminum nitride film, an aluminum nitride oxide film, or the like can be used as the insulating film having a high barrier property. In the case of using a plurality of stacked insulating films, an insulating film such as a silicon oxide film or a silicon oxynitride film having a low nitrogen content is placed closer to the oxide semiconductor layer 7150 than the insulating film having a high barrier property. Form. Then, with the insulating film having a low nitrogen content interposed therebetween, the conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, the conductive film 7210, and the oxide semiconductor layer 7150 are overlapped with each other. An insulating film having a high barrier property is formed. By using an insulating film having a high barrier property, impurities such as moisture or hydrogen are present in the oxide semiconductor layer 7150, the gate insulating film 7140, or the interface between the oxide semiconductor layer 7150 and another insulating film and the vicinity thereof. It can be prevented from entering. Further, by forming an insulating film such as a silicon oxide film or a silicon oxynitride film having a low nitrogen ratio so as to be in contact with the oxide semiconductor layer 7150, the insulating film using a material having a high barrier property can be directly formed. 7150 can be prevented from touching.

In this embodiment, the insulating film 7220 having a structure in which a silicon nitride film with a thickness of 100 nm formed by a sputtering method is stacked over a silicon oxide film with a thickness of 200 nm formed by a sputtering method is formed. The substrate temperature at the time of film formation may be from room temperature to 300 ° C., and is 100 ° C. in this embodiment.

Note that heat treatment may be performed after the insulating film 7220 is formed. The heat treatment is preferably performed at 200 ° C. to 400 ° C., for example, 250 ° C. to 350 ° C. in an atmosphere of nitrogen, ultra-dry air, or a rare gas (such as argon or helium). The gas preferably has a water content of 20 ppm or less, preferably 1 ppm or less, more preferably 10 ppb or less. In this embodiment, for example, heat treatment is performed at 250 ° C. for one hour in a nitrogen atmosphere. Alternatively, before the conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, and the conductive film 7210 are formed, an oxide semiconductor layer for reducing moisture or hydrogen is formed. Similarly to the heat treatment, RTA treatment at a high temperature for a short time may be performed. The heat treatment is performed after the insulating film 7220 containing oxygen is provided, so that oxygen vacancies are generated in the oxide semiconductor layer 7150 due to the previous heat treatment performed on the oxide semiconductor layer. In addition, oxygen is supplied from the insulating film 7220 to the oxide semiconductor layer 7150. Then, by supplying oxygen to the oxide semiconductor layer 7150, oxygen vacancies serving as donors in the oxide semiconductor layer 7150 can be reduced. The oxide semiconductor layer 7150 preferably contains oxygen in an amount exceeding the stoichiometric composition. As a result, the oxide semiconductor layer 7150 can be made to be i-type, variation in electrical characteristics of the transistor due to oxygen deficiency can be reduced, and electrical characteristics can be improved. The timing of performing this heat treatment is not particularly limited as long as it is after the formation of the insulating film 7220, and also serves as another process, for example, heat treatment at the time of resin film formation or heat treatment for reducing the resistance of the transparent conductive film. Thus, the oxide semiconductor layer 7150 can be made to be i-type without increasing the number of steps.

Alternatively, oxygen vacancies serving as donors in the oxide semiconductor layer 7150 may be reduced by performing heat treatment on the oxide semiconductor layer 7150 in an oxygen atmosphere so that oxygen is added to the oxide semiconductor. The temperature of the heat treatment is, for example, 100 ° C. or higher and lower than 350 ° C., preferably 150 ° C. or higher and lower than 250 ° C. The oxygen gas used for the heat treatment under the oxygen atmosphere preferably does not contain water, hydrogen, or the like. Alternatively, the purity of the oxygen gas introduced into the heat treatment apparatus is 6N (99.9999%) or more, preferably 7N (99.99999%) or more (that is, the impurity concentration in oxygen is 1 ppm or less, preferably 0.1 ppm). Or less).

Alternatively, oxygen vacancies serving as donors may be reduced by adding oxygen to the oxide semiconductor layer 7150 by an ion implantation method, an ion doping method, or the like. For example, oxygen that is plasmatized with a microwave of 2.45 GHz may be added to the oxide semiconductor layer 7150.

Note that after a conductive film is formed over the insulating film 7220, the back gate electrode may be formed in a position overlapping with the oxide semiconductor layer 7150 by patterning the conductive film. When the back gate electrode is formed, it is desirable to form an insulating film so as to cover the back gate electrode. The back gate electrode can be formed using the same material and structure as the gate electrode 7130 or the conductive film 7160, the conductive film 7170, the conductive film 7180, the conductive film 7190, the conductive film 7200, and the conductive film 7210.

The thickness of the back gate electrode is 10 nm to 400 nm, preferably 100 nm to 200 nm. For example, after a conductive film having a structure in which a titanium film, an aluminum film, and a titanium film are stacked is formed, a resist mask is formed by a photolithography method or the like, and unnecessary portions are removed by etching, so that the conductive film is desired. It is preferable to form a back gate electrode by processing (patterning) into the shape.

Through the above process, the transistor 7240 is formed.

The transistor 7240 is formed over the gate electrode 7130, the gate insulating film 7140 over the gate electrode 7130, the oxide semiconductor layer 7150 overlapping with the gate electrode 7130 over the gate insulating film 7140, and the oxide semiconductor layer 7150. A pair of conductive films (a conductive film 7200 and a conductive film 7210) is included. Further, the transistor 7240 may include the insulating film 7220 in its constituent elements. A transistor 7240 illustrated in FIG. 19C has a channel-etched structure in which part of the oxide semiconductor layer 7150 is etched between the conductive films 7200 and 7210.

Note that although the transistor 7240 is described using a single-gate transistor, a multi-gate transistor including a plurality of channel formation regions by including a plurality of electrically connected gate electrodes as necessary can be used. Can be formed.

Note that as the insulating film in contact with the oxide semiconductor layer 7150 (in this embodiment, the gate insulating film 7140 and the insulating film 7220 are included), an insulating material containing a Group 13 element and oxygen may be used. good. Many oxide semiconductor materials contain a Group 13 element, and an insulating material containing a Group 13 element has good compatibility with an oxide semiconductor. By using this for an insulating film in contact with the oxide semiconductor layer, oxidation can be performed. The state of the interface with the physical semiconductor layer can be kept good.

An insulating material containing a Group 13 element means that the insulating material contains one or more Group 13 elements. Examples of the insulating material containing a Group 13 element include gallium oxide, aluminum oxide, aluminum gallium oxide, and gallium aluminum oxide. Here, aluminum gallium oxide indicates that the aluminum content (atomic%) is higher than gallium content (atomic%), and gallium aluminum oxide means that the gallium aluminum content (atomic%) contains aluminum. The amount (atomic%) or more is shown.

Alternatively, an inorganic material containing oxygen (such as silicon oxide, silicon oxynitride, or silicon nitride oxide) may be used as the insulating film in contact with the oxide semiconductor layer 7150. By using an inorganic material containing oxygen for the insulating film, oxygen from the insulating film is generated in the oxide semiconductor layer even if oxygen vacancies are generated in the oxide semiconductor layer by heat treatment for reducing moisture or hydrogen. It is possible to reduce oxygen vacancies that are supplied and serve as donors.

For example, when an insulating film is formed in contact with an oxide semiconductor layer containing gallium, the interface characteristics between the oxide semiconductor layer and the insulating film can be kept favorable by using a material containing gallium oxide for the insulating film. . For example, when an oxide semiconductor layer and an insulating film containing gallium oxide are provided in contact with each other, pileup of hydrogen at the interface between the oxide semiconductor layer and the insulating film can be reduced. Note that in the case where an element in the same group as a constituent element of the oxide semiconductor layer is used for the insulating film, a similar effect can be obtained. For example, it is also effective to form an insulating film using a material containing aluminum oxide. Note that aluminum oxide has a characteristic that water is difficult to permeate, and thus the use of the material is preferable in terms of preventing water from entering the oxide semiconductor layer.

The insulating film in contact with the oxide semiconductor layer 7150 is preferably in a state where the amount of oxygen in the insulating material is higher than that in the stoichiometric composition by heat treatment in an oxygen atmosphere, oxygen doping, or the like. Oxygen doping means adding oxygen to the bulk. The term “bulk” is used for the purpose of clarifying that oxygen is added not only to the surface of the thin film but also to the inside of the thin film. The oxygen dope includes oxygen plasma dope in which plasma oxygen is added to the bulk. Further, oxygen doping may be performed using an ion implantation method or an ion doping method.

For example, in the case where gallium oxide is used as the insulating film in contact with the oxide semiconductor layer 7150, the composition of gallium oxide is changed to Ga ₂ O _X (X = 3 + α, 0 <α by performing heat treatment in an oxygen atmosphere or oxygen doping. <1).

In the case where aluminum oxide is used for the insulating film in contact with the oxide semiconductor layer 7150, the composition of the aluminum oxide is changed to Al ₂ O _X (X = 3 + α, 0 <α by performing heat treatment in an oxygen atmosphere or oxygen doping. <1).

In the case where gallium aluminum oxide (aluminum gallium oxide) is used as the insulating film in contact with the oxide semiconductor layer 7150, the composition of gallium aluminum oxide (aluminum gallium oxide) is changed by performing heat treatment in an oxygen atmosphere or oxygen doping. _{Ga X Al 2-X O 3} + α (0 <X <2,0 <α <1) can be.

By performing oxygen doping treatment, an insulating film having a region where oxygen is higher than that in the stoichiometric composition can be formed. When the insulating film including such a region is in contact with the oxide semiconductor layer, excess oxygen in the insulating film is supplied to the oxide semiconductor layer, and the oxide semiconductor layer or the interface between the oxide semiconductor layer and the insulating film is supplied. Thus, the oxide semiconductor layer can be i-type or an oxide semiconductor close to i-type.

Note that the insulating film having a region containing more oxygen than the stoichiometric composition is only one of the insulating film located in the upper layer and the insulating film located in the lower layer among the insulating films in contact with the oxide semiconductor layer 7150. However, it is preferable to use it for both insulating films. By using an insulating film having a region containing more oxygen than the stoichiometric composition as an insulating film located in an upper layer and a lower layer of the insulating film in contact with the oxide semiconductor layer 7150 and sandwiching the oxide semiconductor layer 7150, The above effects can be further enhanced.

The insulating film used for the upper layer or the lower layer of the oxide semiconductor layer 7150 may be an insulating film having the same constituent element in the upper layer and the lower layer, or may be an insulating film having different constituent elements. For example, the upper layer and the lower layer may be gallium oxide having a composition of Ga ₂ O _X (X = 3 + α, 0 <α <1), and one of the upper layer and the lower layer may have a composition of Ga ₂ O _X (X = 3 + α, 0 <Α <1) may be gallium oxide, and the other may be aluminum oxide having a composition of Al ₂ O _X (X = 3 + α, 0 <α <1).

The insulating film in contact with the oxide semiconductor layer 7150 may be a stack of insulating films having a region where oxygen is higher than that in the stoichiometric composition. For example, gallium oxide having a composition of Ga ₂ O _X (X = 3 + α, 0 <α <1) is formed over the oxide semiconductor layer 7150, and the composition thereof is Ga _X Al _{2 -X} O _{3 + α} (0 < You may form the gallium aluminum oxide (aluminum gallium oxide) of X <2, 0 <α <1). Note that the lower layer of the oxide semiconductor layer 7150 may be a stack of insulating films having a region containing more oxygen than the stoichiometric composition, and both the upper layer and the lower layer of the oxide semiconductor layer 7150 may have a stoichiometric composition. An insulating film including a region containing more oxygen may be stacked.

The photodiode 7040 can be used as the photodiode 402 illustrated in FIGS. The n-channel transistor 7050 can be used as the transistor 404 or the transistor 405 illustrated in FIGS. The transistor 7240 can be used as the transistor 403 illustrated in FIGS. The transistor 7240 may be used as the transistor 404 or the transistor 405 illustrated in FIGS.

This embodiment can be implemented in combination with the above embodiment.

(Embodiment 9)
In this embodiment, a transistor in which a channel is formed in an oxide semiconductor layer, which has a structure different from that in Embodiment 8, will be described.

The photosensor illustrated in FIG. 20A includes a photodiode 7040 and an n-channel transistor 7050 as in Embodiment 8. In FIG. 20A, a bottom-gate transistor 7240a having a channel protection structure is formed over the photodiode 7040 and the n-channel transistor 7050.

The transistor 7240a includes a gate electrode 7300 formed over the insulating film 7120, a gate insulating film 7310 over the gate electrode 7300, an oxide semiconductor layer 7320 overlapping with the gate electrode 7300 over the gate insulating film 7310, a gate electrode A channel protective film 7330 formed over the oxide semiconductor layer 7320 and a conductive film 7340 and a conductive film 7350 formed over the oxide semiconductor layer 7320 are provided at positions overlapping with 7300. Further, the transistor 7240a may include an insulating film 7360 formed over the conductive film 7340, the conductive film 7350, and the channel protective film 7330 as its components.

By providing the channel protective film 7330, damage to the portion of the oxide semiconductor layer 7320 that serves as a channel formation region, such as film loss due to plasma or an etchant during etching, in a later step can be prevented. Accordingly, the reliability of the transistor 7240a can be improved.

For the channel protective film 7330, an inorganic material containing oxygen (such as silicon oxide, silicon nitride oxide, silicon oxynitride, aluminum oxide, or aluminum oxynitride) can be used. The channel protective film 7330 can be formed by a vapor deposition method such as a plasma CVD method or a thermal CVD method, or a sputtering method. The channel protective film 7330 is processed by etching after the film formation. Here, a channel protection film 7330 is formed by forming a silicon oxide film by a sputtering method and performing etching using a photolithography mask.

Even when oxygen vacancies are generated in the oxide semiconductor layer 7320 due to heat treatment for reducing moisture or hydrogen by using an inorganic material containing oxygen for the channel protective film 7330, a channel is formed in the oxide semiconductor layer 7320. Oxygen is supplied from the protective film 7330 so that oxygen vacancies serving as donors can be reduced. Thus, the channel formation region can be made closer to i-type, variation in electric characteristics of the transistor 7240a due to oxygen vacancies can be reduced, and improvement in electric characteristics can be realized.

The photosensor illustrated in FIG. 20B includes a photodiode 7040 and an n-channel transistor 7050 as in Embodiment 8. In FIG. 20B, a bottom-contact transistor 7240b is formed over the photodiode 7040 and the n-channel transistor 7050.

The transistor 7240b includes a gate electrode 7410 formed over the insulating film 7120, a gate insulating film 7420 on the gate electrode 7410, a conductive film 7430, a conductive film 7440, and a gate insulating film 7420 on the gate insulating film 7420. And an oxide semiconductor layer 7450 which overlaps with the gate electrode 7410. Further, the transistor 7240b may include an insulating film 7460 formed over the oxide semiconductor layer 7450 as its constituent elements.

Note that the transistors 7240a and 7240b illustrated in FIGS. 20A and 20B may further include a back gate electrode.

The photosensor illustrated in FIG. 20C includes a photodiode 7040 and an n-channel transistor 7050 as in Embodiment 8. In FIG. 20C, a top contact transistor 7240c is formed over the photodiode 7040 and the n-channel transistor 7050.

The transistor 7240c includes the oxide semiconductor layer 7550 formed over the insulating film 7120, the conductive film 7530 and the conductive film 7540 over the oxide semiconductor layer 7550, and the oxide semiconductor layer 7550, the conductive film 7530, and the conductive film 7540. A gate insulating film 7520 and a gate electrode 7510 which overlaps with the oxide semiconductor layer 7550 with the gate insulating film 7520 provided therebetween are provided. Further, the transistor 7240c may include an insulating film 7560 formed over the gate electrode 7510 as its component.

The photosensor illustrated in FIG. 20D includes a photodiode 7040 and an n-channel transistor 7050 as in Embodiment 8. In FIG. 20D, a top contact transistor 7240d is formed over the photodiode 7040 and the n-channel transistor 7050.

The transistor 7240d includes the conductive film 7630 and the conductive film 7640 formed over the insulating film 7120, the oxide semiconductor layer 7650 over the conductive film 7630 and the conductive film 7640, the oxide semiconductor layer 7650, the conductive film 7630, and the conductive film 7640. The upper gate insulating film 7620 and the gate electrode 7610 which overlaps with the oxide semiconductor layer 7650 with the gate insulating film 7620 provided therebetween are included. Further, the transistor 7240d may include an insulating film 7660 formed over the gate electrode 7610 as its component.

The photodiode 7040 can be used as the photodiode 402 illustrated in FIGS. The n-channel transistor 7050 can be used as the transistor 404 or the transistor 405 illustrated in FIGS. The transistors 7240a to 7240d can be used as the transistor 403 illustrated in FIGS. Alternatively, the transistors 7240a to 7240d may be used as the transistor 404 and the transistor 405 illustrated in FIGS.

This embodiment can be implemented in combination with the above embodiment.

(Embodiment 10)
In this embodiment, structures of the adjacent photosensor 700_n and the photosensor 700_ (n + 1) described in Embodiment 3 will be described in more detail. An example of a configuration of an imaging device having photosensors arranged in a matrix of m rows and k columns will be described with reference to FIG. 21, and an example of a configuration different from FIG. 21 will be described with reference to FIG.

FIG. 21 illustrates an example in which the photosensor 700_n and the photosensor 700_ (n + 1) detect reflected light from the same point of the subject in adjacent columns. FIG. 22 illustrates an example in which the photosensor 700_n and the photosensor 700_ (n + 1) detect reflected light from the same point of the subject in adjacent rows. In both configurations, the same effect can be obtained, and the configuration is not limited.

In FIG. 21, a plurality of photosensors are arranged in a matrix of m (m is a natural number of 2 or more) rows k (k is a natural number of 2 or more) columns. For example, reflected light from the same point of the subject is detected in the adjacent photo sensor 700_n and photo sensor 700_ (n + 1) in the first row. Similarly, reflected light from the same point of the subject is detected by the adjacent photo sensor 700_n and photo sensor 700_ (n + 1) in the n-th row.

The n-th column photosensor 700_n (first-row photosensor 700_n to m-th row photosensor 700_n) includes one of a plurality of signal lines 11_n (first row 11_n to m-th row 11_n), It is electrically connected to any one of the plurality of signal lines 12_n (12_n in the first row to 12_n in the m-th row) and one of the plurality of signal lines 13_n (13_n in the first row to 13_n in the m-th row). It is connected.

In addition, the photosensor 700_ (n + 1) in the (n + 1) th column (the photosensor 700_ (n + 1) in the first row to the photosensor 700_ (n + 1) in the mth row) includes a plurality of signal lines 11_ (n + 1) (one row). Any one of 11_ (n + 1) to mth row 11_ (n + 1)) and a plurality of signal lines 12_ (n + 1) (first row 12_ (n + 1) to mth row 12_ (n + 1)) Any one of them is electrically connected to any one of a plurality of signal lines 13_ (n + 1) (first row 13_ (n + 1) to mth row 13_ (n + 1)).

The photosensor 700_n in the n-th column (the photosensor 700_n in the first row to the photosensor 700_n in the m-th row) shares the photosensor output signal line and the photosensor reference signal line. For example, the n-th column photosensor output signal line (represented as 16_n) is electrically connected to the n-th column photosensor 700_n (first row photosensor 700_n to mth row photosensor 700_n), The n-th column photosensor reference signal line (denoted as 15_n) is also electrically connected to the n-th column photosensor 700_n (first row photosensor 700_n to mth row photosensor 700_n). .

Further, the photosensor 700_ (n + 1) in the (n + 1) th column (the photosensor 700_ (n + 1) in the first row to the photosensor 700_ (n + 1) in the mth row) includes a photosensor output signal line and a photosensor reference signal line. Share. For example, the (n + 1) th column photosensor output signal line (represented as 16_ (n + 1)) is the (n + 1) th column photosensor 700_ (n + 1) (first row photosensor 700_ (n + 1) to mth row). The photosensor reference signal line (denoted as 15_ (n + 1)) in the (n + 1) th column is also electrically connected to the photosensor 700_ (n + 1) in the (n + 1) th column. ) (Photo sensor 700_ (n + 1) in the first row to photo sensor 700_ (n + 1) in the m-th row).

In FIG. 21, the photosensor reference signal line 15_n is shared by the photosensors in the nth column, and the photosensor reference signal line 15_ (n + 1) is shared by the photosensors in the (n + 1) th column. Further, the photosensor output signal line 16_n is shared by the photosensors in the nth column, and the photosensor output signal line 16_ (n + 1) is shared by the photosensors in the (n + 1) th column.

However, the present invention is not limited to this. For example, a plurality of photosensor reference signal lines 15 may be provided in each column and electrically connected to different photosensors. Further, a plurality of photosensor output signal lines 16 may be provided in each column and electrically connected to different photosensors.

FIG. 21 shows a configuration in which the photosensor reference signal line 15 and the photosensor output signal line 16 are shared by the photosensors in each column, but the present invention is not limited to this. The photo sensor reference signal line 15 and the photo sensor output signal line 16 may be shared by the photo sensors in each row.

By sharing wiring and reducing the number of wirings as described above, a driving circuit for driving photosensors arranged in a matrix of m rows and k columns can be simplified.

Next, an example of a configuration different from that in FIG. 21 of the imaging device having photosensors arranged in a matrix of m rows and k columns will be described with reference to FIG. In FIG. 22, a plurality of photosensors are arranged in a matrix of m (m is a natural number of 2 or more) rows k (k is a natural number of 2 or more) columns. For example, reflected light from the same point of the subject is detected in the adjacent photosensor 700_n and photosensor 700_ (n + 1) in the first row. Similarly, reflected light from the same point of the subject is detected by the photosensor 700_n and the photosensor 700_ (n + 1) adjacent to the nth column.

The photosensor 700_n in the n-th row (the photosensor 700_n in the first column to the photosensor 700_n in the k-th column) has one of a plurality of signal lines 11_n (11_n in the first column to 11_n in the k-th column), Any one of a plurality of signal lines 12_n (12_n in the first column to 12_n in the k-th column) and any one of a plurality of photosensor output signal lines 16_n (16_n in the first column to 16_n in the k-th column) Electrically connected.

The photosensor 700_ (n + 1) in the (n + 1) th row (the photosensor 700_ (n + 1) in the first column to the photosensor 700_ (n + 1) in the kth column) includes a plurality of signal lines 11_ (n + 1) (in the first column). Any one of 11_ (n + 1) to 11_ (n + 1) in the kth column and a plurality of signal lines 12_ (n + 1) (12_ (n + 1) in the first column to 12_ (n + 1) in the kth column) One of the photosensor output signal lines 16_ (n + 1) (16_ (n + 1) in the first column to 16_ (n + 1) in the kth column) is electrically connected.

The photosensor 700_n in the n-th row (the photosensor 700_n in the first column to the photosensor 700_n in the k-th column) shares the signal line 13_n. The photosensor 700_ (n + 1) in the (n + 1) th row (the photosensor 700_ (n + 1) in the first column to the photosensor 700_ (n + 1) in the kth column) shares the signal line 13_ (n + 1). . For example, the signal line 13_n in the nth row is electrically connected to the photosensor 700_n in the nth row (the photosensor 700_n in the first column to the photosensor 700_n in the kth column), and the signal line in the (n + 1) th row. 13_ (n + 1) is electrically connected to the photosensor 700_ (n + 1) in the (n + 1) th row (the photosensor 700_ (n + 1) in the first column to the photosensor 700_ (n + 1) in the kth column).

The photosensor reference signal line 15 is shared by the photosensors in each column. For example, as shown in FIG. 22, the photosensor reference signal line 15 is shared by the photosensors in the first column, the photosensor reference signal line 15 is shared by the photosensors in the second column, and the photosensors in the kth column. The photo sensor reference signal line 15 is shared.

However, the present invention is not limited to this. For example, a plurality of photosensor reference signal lines 15 may be provided in each column and electrically connected to different photosensors.

Note that although FIG. 22 shows a configuration in which the photosensor reference signal line 15 is shared by the photosensors in each column and the signal line 13 is shared by the photosensors in each row, the present invention is not limited to this. The photosensor reference signal line 15 may be shared by the photosensors in each row, or the signal line 13 may be shared by the photosensors in each column.

By sharing wiring and reducing the number of wirings as described above, a driving circuit for driving photosensors arranged in a matrix of m rows and k columns can be simplified.

Note that the structures of the photosensor 700_n and the photosensor 700_ (n + 1) are similar to those of the photosensor 400 described above; therefore, a top view and a cross-sectional view of these photosensors are illustrated in FIGS. ) Can be referred to.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 11)
In this embodiment, an example of a structure in which a plurality of photosensors included in an imaging device are arranged in matrix will be described with reference to FIGS. Note that Embodiment 4 can be referred to for the configuration and driving method of the photosensor.

In FIG. 23A, a plurality of photosensors 800 are arranged in a matrix of m (m is a natural number of 2 or more) rows n (n is a natural number of 2 or more) columns. The photosensor 800 in each row includes any one of a plurality of signal lines 11A (reset signal lines) (denoted as 11A_1 to 11A_m) and a plurality of signal lines 12A (charge storage signal lines) (denoted as 12A_1 to 12A_m). And any one of a plurality of signal lines 13A (selection signal lines) (denoted as 13A_1 to 13A_m) and a plurality of signal lines 11B (reset signal lines) (denoted as 11B_1 to 11B_m) Or any one of a plurality of signal lines 12B (charge storage signal lines) (denoted as 12B_1 to 12B_m) and any of a plurality of signal lines 13B (selection signal lines) (denoted as 13B_1 to 13B_m). One and a plurality of signal lines 15 (photo sensor reference signal lines) (denoted as 15_1 to 15_n) are electrically connected. Shows an example in which. The photosensor 800 in each column includes any one of a plurality of signal lines 16A (photosensor output signal lines) (indicated as 16A_1 to 16A_n) and a plurality of signal lines 16B (photosensor output signal lines) (16B_1 to 16B_n). And an example of being electrically connected.

In FIG. 23, in each row of photosensors 800, the signal line 11A (reset signal line), the signal line 12A (charge storage signal line), the signal line 13A (selection signal line), the signal line 11B (reset signal line), and the signal line 12B (Charge storage signal line), signal line 13B (selection signal line), and signal line 15 (photosensor reference signal line) are shared. Further, the photosensor 800 in each row shares a signal line 16B (photosensor output signal line) and a signal line 16A (photosensor output signal line).
Note that connection of signal lines is not limited to the above structure.

FIG. 23 illustrates the configuration in which the signal line 15 (photosensor reference signal line) is shared by the photosensors 800 in each row, but is not limited thereto. The signal line 15 (photosensor reference signal line) may be shared by the photosensors 800 in each column.

In FIG. 23B, the first photodiode 802A (802A_1 to 802A_n) in the first photosensor 800A and the second photodiode 802B (802B_1 to 802B_n) in the second photosensor 800B are provided. Indicates placement. Here, the light reflected from the object to be detected first enters the first photodiode 802A (802A_1 to 802A_n). Therefore, the light reflected from the detected object is irradiated with one or both of light from the light source and natural light to the detected object, reflected from the detected object, and the first photodiode 802A. And the infrared light incident on the second photodiode 802 </ b> B after being irradiated from the light source to the object to be detected and reflected from the object to be detected.

Amorphous silicon which is a semiconductor layer of the first photodiode 802A which is a visible light sensor has a characteristic of absorbing visible light incident from the outside and transmitting infrared light incident from the outside. With the above structure, visible light can be mainly absorbed by the first photodiode 802A (802A_1 to 802A_n), and infrared light can be mainly absorbed by the second photodiode 802B (802B_1 to 802B_n). become. In addition, incidence of visible light on the second photodiode, which is an infrared light sensor, can be reduced. Therefore, the first photosensor 800A can be used for two-dimensional imaging with visible light, and the second photosensor 800B can be used for three-dimensional imaging with infrared light, so that the area occupied by the photosensor can be reduced. it can.

As described above, in the configuration of this embodiment, the first photosensor 800A that is a visible light sensor and the second photosensor 800B that is an infrared light sensor are provided so as to overlap with each other. The area occupied by the photosensor 800 can be reduced. As a result, it is possible to perform one-time imaging of two-dimensional imaging and three-dimensional imaging using the TOF method while achieving pixel miniaturization.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

(Embodiment 12)
In this embodiment mode, FIG. 24 shows a top view of the photosensor shown in FIGS. In addition, a cross-sectional view corresponding to one-dot chain lines A1-A2 and A3-A4 in FIG. 24 is shown in FIG. 25A, and a cross-sectional view corresponding to one-dot chain line B1-B2 in FIG. 24 is shown in FIG. .

FIG. 25A will be described. In FIG. 25A, a light-blocking layer 831 and a base film 832 are provided over a light-transmitting substrate 880. A p-type semiconductor region 883 and an i-type semiconductor region 884 in the second photodiode 802B are provided over the light-blocking layer 831 with a base film 832 interposed therebetween. The n-type semiconductor region 885 and the i-type semiconductor region constituting the semiconductor layer of the first transistor 804B are formed in the same layer as the semiconductor layer constituting the p-type semiconductor region 883 and the i-type semiconductor region 884 in the second photodiode 802B. 886 is provided. Similarly, an n-type semiconductor region 887 and an i-type semiconductor layer constituting the semiconductor layer of the second transistor 805B are formed in the same layer as the semiconductor layer constituting the p-type semiconductor region 883 and the i-type semiconductor region 884 in the second photodiode 802B. A semiconductor region 888 is provided. Similarly, an n-type semiconductor region 889 constituting the semiconductor layer of the third transistor 803A is provided in the same layer as the semiconductor layer constituting the p-type semiconductor region 883 and the i-type semiconductor region 884 in the second photodiode 802B. .

Note that the light-transmitting substrate 880 is preferably a substrate having a light-transmitting property with respect to visible light and infrared light. For example, a plastic substrate having a light-transmitting property with respect to visible light and infrared light, or a glass substrate having a light-transmitting property with respect to visible light and infrared light can be used.

Note that the light-blocking layer 831 is for preventing infrared light and visible light from the backlight from entering the first photodiode 802A and the second photodiode 802B. The light-blocking layer 831 is formed by a sputtering method, a CVD method, or a coating method using a metal material such as aluminum or chromium that can block infrared light and visible light, and then processed by using a photolithography method and an etching method. It is formed. Note that the light-blocking layer 831 is preferably provided not only in a region stacked with the second photodiode 802B but also in a region stacked with a semiconductor layer of each transistor included in the transistors 803, 804, and 805. Since the semiconductor layer of each transistor is shielded by the light-shielding film, it is possible to prevent deterioration of characteristics such as shift of the threshold voltage of the transistor due to incidence of infrared light and visible light from the backlight. In addition, as a structure of a backlight, what is necessary is just a structure using the light source which can light-emit infrared light and visible light from the translucent board | substrate 880 side. Specifically, the backlight may have a structure in which a light emitting diode that emits infrared light and a light emitting diode that emits visible light are arranged side by side.

Here, the backlight is provided on the light-transmitting substrate 880 side so that visible light and infrared light for detecting light are incident on the first photodiode 802A and the second photodiode 802B. Note that the light-emitting diode that emits infrared light may be separately provided on the counter substrate side.

Note that the base film 832 prevents alkali metal such as Na or alkaline earth metal contained in the light-transmitting substrate 880 from diffusing into the second photodiode 802B and adversely affecting the characteristics. The base film 832 is formed by a single layer or a stack of light-transmitting and insulating materials such as silicon oxide, silicon nitride, silicon oxynitride, and silicon nitride oxide by a CVD method, a sputtering method, or the like. Note that the surface of the base film 832 preferably has high flatness. This is to prevent formation defects when the semiconductor layer of the second photodiode 802B is formed.

Note that crystalline semiconductor such as polycrystalline silicon can be used for a semiconductor layer of the second photodiode 802B. In the second photodiode 802B formed using a semiconductor layer including crystalline silicon, a p-type semiconductor region 883, an i-type semiconductor region 884, and an n-type semiconductor region (not shown) are arranged in a horizontal direction on the light-transmitting substrate 880. Provided. The semiconductor layers of the transistors included in the transistors 803, 804, and 805 are also provided with an n-type semiconductor region, an i-type semiconductor region, and an n-type semiconductor region using crystalline silicon such as polycrystalline silicon. For the second photodiode 802B and the semiconductor layer of each transistor, the formed crystalline silicon is processed by photolithography and etching, and then a p-type or n-type impurity region is masked by photolithography. After forming, it is formed by ion implantation or ion doping.

Note that the semiconductor layer of the second photodiode 802B can be formed using crystalline silicon such as single crystal silicon by a bonding or peeling method. First, hydrogen ions (such as H ⁺ , H ₂ ⁺ , H ₃ ⁺ ) or hydrogen ions and helium ions are added to a semiconductor wafer such as a silicon wafer to form an embrittlement layer in the semiconductor wafer. The semiconductor wafer is bonded to the base film 832 and separated from the embrittlement layer by heat treatment, so that a semiconductor layer is formed over the base film 832. Since the depth from the surface of the semiconductor wafer to the embrittlement layer corresponds to the thickness of the semiconductor layer, the thickness of the semiconductor layer can be adjusted by controlling the addition conditions such as hydrogen ions.

In FIGS. 24 and 25A, the semiconductor layer of the second photodiode 802B, the semiconductor layer of the first transistor 804B, the semiconductor layer of the second transistor 805B, and the semiconductor layer of the third transistor 803A are An insulating layer 810 is provided. A gate electrode 811 formed in the same layer as the transfer control line 807 and the power supply line 808 is provided over the i-type semiconductor region 886 with an insulating layer 810 interposed therebetween. A gate electrode 812 formed in the same layer as the transfer control line 807 and the power supply line 808 is provided over the i-type semiconductor region 888 with an insulating layer 810 interposed therebetween. On the insulating layer 810, a power supply line 808 formed in the same layer as the transfer control line 807 is provided.

Note that the insulating layer 810 prevents an alkali metal such as Na or an alkaline earth metal from diffusing into the second photodiode 802B from the outside and adversely affecting the characteristics. The insulating layer 810 is formed using a single layer or a stacked layer of a light-transmitting and insulating material such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, or an organic resin film by a plasma CVD method, a sputtering method, or the like. To form.

Note that various wirings formed in the same layer as the gate electrode 811 and the gate electrode 812 may be formed using a conductive metal material. As a conductive metal material, a metal layer such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, scandium, or an alloy material containing these as a main component is used to form a single layer or a stacked layer. To do. It is formed using a sputtering method or a vacuum evaporation method.

In FIGS. 24 and 25A, an insulating layer 813 is provided over the insulating layer 810, the gate electrode 811, the gate electrode 812, and the power supply line 808. Between the n-type semiconductor region 885 and the n-type semiconductor region 887, the first output signal line 840A and the second output signal line 840B are formed in the same layer with the insulating layer 810 and the insulating layer 813 interposed therebetween. A conductive layer 814 is provided. A second output signal line 840B is provided over the n-type semiconductor region 887 with the insulating layer 810 and the insulating layer 813 interposed therebetween. Between the n-type semiconductor region 885 and the power supply line 808, a conductive layer formed in the same layer as the first output signal line 840A and the second output signal line 840B with the insulating layer 810 and the insulating layer 813 interposed therebetween. 815 is provided. Over the p-type semiconductor region 883, a conductive layer 816 formed in the same layer as the first output signal line 840A and the second output signal line 840B is provided with the insulating layer 810 and the insulating layer 813 interposed therebetween. A conductive layer 817 formed in the same layer as the first output signal line 840A and the second output signal line 840B is provided over the n-type semiconductor region 889 with the insulating layer 810 and the insulating layer 813 interposed therebetween.

Note that the insulating layer 813 is formed using a single layer or a light-transmitting and insulating material such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, or an organic resin film by a plasma CVD method, a sputtering method, or the like. It is formed by stacking.

Note that the conductive layers 814 to 817 are formed by a sputtering method or a vacuum evaporation method using a metal such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, or yttrium, an alloy material containing these as a main component, or an oxide. A material such as a conductive metal oxide such as indium is formed in a single layer or a stacked layer.

In FIG. 25A, a p-type semiconductor region 818, an i-type semiconductor region 819, and an n-type semiconductor region 820 in the first photodiode 802A are provided over the insulating layer 813 and the conductive layer 816. Note that the p-type semiconductor region 818 in the first photodiode 802 </ b> A is provided so as to overlap with the conductive layer 816 and the end portion.

Note that amorphous semiconductor can be used for a semiconductor layer of the first photodiode 802A. In the first photodiode 802A including a semiconductor layer including amorphous silicon, a p-type semiconductor region 818, an i-type semiconductor region 819, and an n-type semiconductor region 820 are stacked in a direction perpendicular to the light-transmitting substrate 880. Provided.

The p-type semiconductor region 818 is formed using amorphous silicon containing an impurity element imparting p-type conductivity. The p-type semiconductor region 818 is formed by a plasma CVD method using a semiconductor material gas containing a Group 13 impurity element (eg, boron (B)). Silane (SiH ₄ ) may be used as the semiconductor material gas. Alternatively, Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _4, or the like may be used. The p-type semiconductor region 818 is preferably formed to have a thickness of 10 nm to 50 nm.

The i-type semiconductor region 819 is formed of amorphous silicon. For the formation of the i-type semiconductor region 819, amorphous silicon is formed by a plasma CVD method using a semiconductor material gas. Silane (SiH ₄ ) may be used as the semiconductor material gas. Alternatively, Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _4, or the like may be used. The i-type semiconductor region 819 is preferably formed to have a thickness of 880 nm to 8000 nm.

The n-type semiconductor region 820 is formed using amorphous silicon containing an impurity element imparting n-type conductivity. The n-type semiconductor region 820 is formed by a plasma CVD method using a semiconductor material gas containing a Group 15 impurity element (for example, phosphorus (P)). Silane (SiH ₄ ) may be used as the semiconductor material gas. Alternatively, Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _4, or the like may be used. The n-type semiconductor region 820 is preferably formed to have a thickness of 20 nm to 880 nm.

In FIG. 25A, an insulating layer 821 is provided over the first photodiode 802A, the second output signal line 840B, the conductive layer 814, the conductive layer 815, the conductive layer 816, and the conductive layer 817. Between the n-type semiconductor region 820 and the conductive layer 817, a conductive layer 822 formed in the same layer as the conductive layer to be a pixel electrode is provided with an insulating layer 821 interposed therebetween.

Note that the insulating layer 821 is formed using a single layer or a light-transmitting and insulating material such as a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, or an organic resin film by a plasma CVD method, a sputtering method, or the like. It is formed by stacking. Note that the insulating layer 821 is preferably an insulating layer having a flat surface.

Note that the conductive layer 822 may be a light-transmitting conductive layer, such as indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), or indium zinc oxide (Indium Zinc Oxide). ) Or the like.

Next, FIG. 25B will be described. In the cross-sectional view in FIG. 25B, a light-blocking layer 831 and a base film 832 are provided over a light-transmitting substrate 880. A p-type semiconductor region 883, an i-type semiconductor region 884, and an n-type semiconductor region 823 in the second photodiode 802B are provided over the light-blocking layer 831 with a base film 832 interposed therebetween.

In FIG. 25B, an insulating layer 810 is provided over the semiconductor layer in the second photodiode 802B. On the insulating layer 810, a power supply line 808 formed in the same layer as the transfer control line 807 is provided.

In FIGS. 24 and 25B, an insulating layer 813 is provided over the insulating layer 810 and the power supply line 808. Over the p-type semiconductor region 883, a conductive layer 816 formed in the same layer as the first output signal line 840A and the second output signal line 840B is provided with the insulating layer 810 and the insulating layer 813 interposed therebetween. A conductive layer 824 formed in the same layer as the first output signal line 840A and the second output signal line 840B is provided over the n-type semiconductor region 823 with the insulating layer 810 and the insulating layer 813 interposed therebetween.

In FIG. 25B, the p-type semiconductor region 818, the i-type semiconductor region 819, and the n-type semiconductor region 820 in the first photodiode 802A are provided over the insulating layer 813 and the conductive layer 816. Note that the p-type semiconductor region 818 in the first photodiode 802 </ b> A is provided so as to overlap with the conductive layer 816 and the end portion.

In addition, an insulating layer 821 is provided over the first photodiode 802A, the conductive layer 816, and the conductive layer 824 in the cross-sectional view shown in FIG.

Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.

DESCRIPTION OF SYMBOLS 1 Transmission number 2 Transmission number 3 Transmission number 11 Signal line 12 Signal line 13 Signal line 14 Node 15 Signal line 16 Signal line 17 Signal line 18 Node 100 Motion recognition apparatus 101 Imaging apparatus 102 Image processing apparatus 103 Information processing apparatus 104 Imaging data 105 Output data 110 Image storage unit 111 Storage unit 112 Storage unit 113 Storage unit 114 Storage unit 115 Object data detection unit 116 Operation data detection unit 117 Output control unit 210 Conductive film 211 Conductive film 212 Conductive film 213 Conductive film 214 Conductive film 215 Semiconductor film 216 semiconductor film 217 semiconductor film 218 conductive film 219 conductive film 220 conductive film 221 conductive film 222 conductive film 223 conductive film 225 conductive film 226 conductive film 227 conductive film 228 gate insulating film 250 semiconductor layer 251 substrate 281 insulating film 282 insulating Film 400 photo Sensor 401 Circuit 402 Photodiode 403 Transistor 404 Transistor 405 Transistor 406 Transistor 501 Pulse 502 Pulse 601 Pulse 602 Pulse 700 Photo sensor 702 Photo diode 703 Transistor 704 Transistor 705 Transistor 800 Photo sensor 800A Photo sensor 800B Photo sensor 802 Photo diode 802A Photo diode 802B Photodiode 803 Transistor 803A Transistor 803B Transistor 804 Transistor 804A Transistor 804B Transistor 805 Transistor 805A Transistor 805B Transistor 807 Transfer control line 808 Power supply line 810 Insulating layer 811 Gate electrode 812 Gate electrode 813 Insulating layer 81 Conductive layer 815 Conductive layer 816 Conductive layer 817 Conductive layer 818 P-type semiconductor region 819 i-type semiconductor region 820 n-type semiconductor region 821 Insulating layer 822 Conductive layer 823 n-type semiconductor region 824 Conductive layer 831 Light shielding layer 832 Base film 840A Output signal line 840B Output signal line 880 Translucent substrate 883 p-type semiconductor region 884 i-type semiconductor region 885 n-type semiconductor region 886 i-type semiconductor region 887 n-type semiconductor region 888 i-type semiconductor region 889 n-type semiconductor region 901 pulse 902 pulse 5000 portable Telephone 5001 Speaker 5002 Case 5003 Display unit 5004 Operation button 5005 Recognition range 6000 IH cooking heater 6001 Display unit 6001a Display unit 6001b Display unit 6001c Display unit 6002a IH heater 6002b IH heater 6002c IH heater 6003 Plate 6004 Power lamp 6005 Operation button 6006 Exhaust port 6007a Recognition range 6007b Recognition range 6007c Recognition range 7000 Microwave oven 7001 Display 7002 Operation button 7003 Window 7004 Open / close door handle 7005 Housing 7006 Open / close door 7007 Recognition range 7008 Power lamp 7010 Insulating film 7020 Semiconductor film 7030 Semiconductor film 7040 Photodiode 7050 N-channel transistor 7060 Substrate 7070 Gate electrode 7080 Insulating film 7110 Wiring 7120 Insulating film 7130 Gate electrode 7140 Gate insulating film 7150 Oxide semiconductor layer 7160 Conductive film 7170 Conductive film 7180 Conductive Film 7190 conductive film 7200 conductive film 7210 conductive film 7220 insulating film 7240 transistor 7240a transistor Transistor 7240b transistor 7240c transistor 7240d transistor 7270 region 7280 region 7290 region 7300 gate electrode 7310 gate insulating film 7320 oxide semiconductor layer 7330 channel protective film 7340 conductive film 7350 conductive film 7360 insulating film 7410 gate electrode 7420 gate insulating film 7430 conductive film 7440 conductive Film 7450 oxide semiconductor layer 7460 insulating film 7510 gate electrode 7520 gate insulating film 7530 conductive film 7540 conductive film 7550 conductive film 7550 oxide semiconductor layer 7560 insulating film 7610 gate electrode 7620 gate insulating film 7630 conductive film 7640 conductive film 7650 oxide semiconductor layer 7660 insulating film

Claims (2)

An imaging device, an image processing device, and an information processing device;
The imaging device acquires distance image information of an object to be detected, generates imaging data from the distance image information, and outputs the imaging data ;
The image processing apparatus includes:
A first storage unit for storing the specific object pattern;
A second storage unit for storing the specific operation pattern;
An image storage unit that stores the imaging data that changes over time;
Extracting the imaging data from the operation start time to the operation end time of the detected object from the imaging data stored in the image storage unit, and comparing the extracted imaging data with the specific object pattern An object data detection unit that selects the most consistent object data at each time;
A third storage unit for storing the object data at each time;
A motion data detector that estimates motion data by comparing the object data from the motion start time to the motion end time of the detected object stored in the third storage unit with the specific motion pattern; A fourth storage unit for storing operation data;
An output control unit that generates output data from the operation data and outputs the output data ;
Have
The information processing apparatus recognizes an operation of the detected object based on the output data, and executes an operation defined based on the output data ;
The imaging device
Start irradiation of the first light from the light source to the detected object,
The first reflected light reflected by the object to be detected begins to enter the imaging device;
Ending irradiation of the first light from the light source to the object to be detected;
Incident of the first reflected light to the imaging device is terminated,
Obtaining a first detection signal;
Starting irradiation of the second light from the light source to the object to be detected;
Second reflected light reflected by the object to be detected is incident on the imaging device,
Ending the irradiation of the second light from the light source to the detected object,
Incident of the second reflected light to the imaging device is terminated,
Sequentially obtaining the second detection signal;
The first detection signal is incident on the photodiode during a period from when the first reflected light starts to enter the imaging device to when the irradiation of the first light from the light source to the detected object is completed. According to the amount of the first reflected light,
The second detection signal is a period from the end of the irradiation of the second light to the detected object from the light source to the end of incidence of the second reflected light on the imaging device. Depending on the amount of the second reflected light incident on the photodiode;
A distance from the light source to the object to be detected is calculated using the first detection signal and the second detection signal . In claim 1,
The operation recognition device, wherein the photodiode has a channel formation region electrically connected to a transistor including an oxide semiconductor.